Complete Monster/Kamen Rider

Not all Kamen Riders are heroes...

Kamen Rider has been around since 1971, with its main theme being about how someone can rise above tragedy to become a hero and while many villains have redeeming qualities, these are the very worst that have none.

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Franchise-Wide

• The Great Leader of Shocker serves as the overarching Big Bad of the Showa Era and an archetype to many of his successors of the Henshin genre. Desiring to rule the world, he kidnaps countless innocents to experiment on and brainwashes them into becoming his soldiers, even torturing them with electricity to test them. When his organization Shocker would start to falter by the efforts of the heroes, he founded Gel-Shocker, slaughtering all of his soldiers in retribution for their failures. He then resurfaced in V3, where he would create the organization Destron and attempted to launch Operation: Japan Annihilation, which would release Deadly Gas across the entire country and take the lives of millions and he even attempted to throw his own son in a pool of acid for defying him. He resurfaced again in Skyrider, where he manipulates the Neo-Shocker group to gain more power, attempting to wipe out the world's oxygen and exterminate humanity to spite the Riders. In the movie OOO, Den-O, All Riders: Let's Go Kamen Riders, he resurfaces as the final villain to use time travel to conquer the world, even murdering his own generals to achieve victory, believing in achieving power for himself no matter what the cost. Defined by his monstrous God Complex and desire to remake the world in his own image, the Great Leader of Shocker represents the very worst the franchise has to offer.
• Takeshi Asakura/Kamen Rider Ouja is the archetypical evil Rider of the Heisei Era, is a psychopath who is drawn to, and wishes to perpetuate, violence. Originally an escaped Serial Killer who joined the Rider Fight, Asakura murdered his own family at the age of 13 by starting a fire in their home, and would go on to rack up the highest body count amongst the Riders. A vicious sadist, he's responsible for breaking the hands of the intended Kamen Rider Raia, Yuichi Saito, and the murder of an innocent woman, who turns out to be Miho Kirishima's sister, thus making getting revenge her reason for becoming Kamen Rider Femme; Asakura would later use a child as monster bait, with him willing to let her be killed to fuel his thrill for carnage. To top it all off, he kills his own estranged brother by feeding the latter to his Contract Monster, Venosnaker. Revived in 2017 by Foundation X, Asakura leads the Beast Rider Squad and terrorizes the Cyber Rescue team, beginning his new series of crimes by murdering a police officer and beating Satsuki until both of her arms were broken. Confronted by Emu Hojo, Asakura pushes his head into a bucket of glass and uses two of his comrades as Human Shields during his battle against Hiiro Kagami, killing them. Brought back in 2019 as one of the six returning veterans to participate in the new Rider Fight, Asakura is "thrilled for the party to start again", killing Tozuka, Ren and Goro, whom he had promised to kill for last if he kept cooking for him. Asakura's evil is so great that it lives on in the franchise, with Asakura acting as a Fountain of Expies for numerous other villains.

Showa Series

• Kamen Rider (TV series):
  • Colonel Bakarashin Iinodevitch Zol is a former SS officer who lost his left eye when gas leaked from one of the chambers at the Auschwitz camp. Proud of his war crimes and his past as a high-ranking Nazi, Zol joined Shocker's Middle East Branch after the end of World War II and quickly got a reputation for brutality. Transferred to Japan to deal with Kamen Rider 2, Zol brainwashes children into becoming Child Soldiers for Shocker and gases an entire town. Apathetic to the fates of his own soldiers, Zol dismisses their deaths and even tests the powers of a resurrected mummy-like Kaijin by letting him murder one of his mooks. Using another infectious Kaijin, Zol has him kill a group of innocents, forcibly converting the survivor into a disease-carrier to spread more suffering.
  • General Black is the sole commander of Gel-Shocker and the Great Leader's representative after the fall of Shocker. Originally a young conscript in the Imperial Russian Army, Black stood out as a Sociopathic Soldier who caught the attention of Nikolai II himself, rising to the top of the military hierarchy with his sadistic methods. After the Empire collapsed, Black was invited to join Geldam and traveled to the African deserts, training their soldiers there. When the Great Leader proposed to merge their organizations in an alliance, Black gladly accepted the offer and provided him with a new generation of operatives, sending his underling to hunt down the Shocker soldiers who were marked for execution; all Gel-Shocker soldiers must take a drug called Gelper every three hours, or else they combust alive. Given the task of eliminating the Shocker scientists, Black releases them, only to gas their bus in an experiment. Putting the lives of millions of people at risk with his plans, Black sends a Kaijin to test his abilities by unleashing his corrosive gas inside an entire apartment complex, and orders the mass kidnapping of civilians to expand Gel-Shocker's personnel by performing surgery on them whenever he feels like it, later brainwashing children to be part of a new unit of Child Soldiers and almost making them consume Gelper.
• Kamen Rider V 3: Marshal Armor is the fourth and final Destron Commander. When he assumes command of Destron, his first act is to plant evidence against their head scientist, Jōji Yuki, whom he views as a threat, and execute him via acid pit. Knowing the man values his hands for his work, Armor begins the execution by burning one off first. From there, Armor launches a number of deadly schemes, including attempting to cover Tokyo in nerve gas, kidnapping children for slave labor, and unleashing Vampire-Chameleon on more children to feed off their blood. When Vampire-Chameleon kills a pair of his own men, Armor coldly remarks that if they weren't so weak they wouldn't have died. When ordered by the Destron Leader to launch a nuclear assault on Tokyo, Armor kidnaps a scientist's family to force him to work on the weapon. When he frees the heroes, Armor has him killed, and hangs his corpse outside the Destron base as a warning to all who would defy him.
• Kamen Rider Amazon: Ten-Faced Demon Gorgos is the leader of Geddon and a brutal sadist with a taste for human blood—which gives him power—and giving ironic deaths to his own men. A subordinate to Ruler, Gorgos is introduced pouring incendiary blood over the Amazon rainforest, burning a tribe alive and wounding Daisuke Yamamoto. In his mission to defeat Daisuke and obtain his bracelet, Gorgos punishes those who dare to fail him, through such means as burning; consumption by vampire bats; and exposure to the sun. Gorgos makes sure to ruin Daisuke's life by killing people close to him, and laughing at their deaths. In one occasion, Gorgos discovered that Daisuke was a close friend to a little girl, and he had her father Eaten Alive by a giant snake. After kidnapping several students from an elementary school, Gorgos has them tied to the ceiling and tortured with hot gas. Growing bored of drinking men's blood, Gorgos uses his servants to try and capture young women, and later children, for him to drain their blood. Capturing a human criminal, Gorgos turns him into the Ant Beastman, praising him for his violence even after he had attacked his own allies. Before his ultimate defeat, Gorgos invaded a local university and slaughtered multiple people with acid.
• Kamen Rider Stronger: Mr. Titan is the first and worst executive of Black Satan. Once a suave criminal who quickly jumped into the opportunity to join Black Satan, Titan rose through their ranks until he became one of the Great Leader's Co-Dragons, supervising and overseeing the Kikkaijin on the field to make sure that they are successful while being cruel towards his own men; Titan is involved in numerous destructive operations, including but not limited to: tainting the school lunches of elementary school students with capsules of Tetrodotoxin; contaminating the water supply of a town with a chemical that induces homicidal insanity; and using a cacophonic sound to make adults kill children. When Titan gets his hands on the Gamma Bugs, parasites that are capable of killing their hosts, he tests their properties on a captive and makes the man strangle himself to death for fun, planning on spreading the Gamma Bugs over Tokyo to help Black Satan in controlling the city, and when that fails, Titan tries to assassinate a sheik to disrupt international relations. Recruiting Black Satan's strongest Kikkaijin to assist him in a plan to export poisoned food worldwide to kill millions and allow Japan to be invaded, Titan is killed after sacrificing a Kikkaijin in an attempt to kill Shigeru Jo. Revived by the Great Leader, Titan earns the enmity of his rival General Shadow for using dirty tactics to win, with one of his first plans after his return being mass-producing a bioweapon for Black Satan, forcing an innocent prisoner to inhale it. Defeated yet again, Titan proposes a handshake before he dies to show that he respects Jo, only to reveal that it was a trick to take Jo to hell with him.
• Kamen Rider Black: While Gorgom was a cult led by literal monsters, these two Psycho Supporters prove that Humans Are the Real Monsters:
  • Professor Hideomi Kuromatsu is a Nobel Prize winning researcher who moonlights as Gorgom's chief scientist. This man responsible for converting victims into mutants, Kuromatsu's MO is to propose a Deal with the Devil to young men, promising to make their bodies stronger by performing an experiment that makes them worse, which once resulted in a suicide. After making a deal with Kohtaro's close friend, Kuromatsu turns him into a Wolf Man and confesses to using him as a guinea pig. Kuromatsu orders his subordinates to cause several car accidents for him to save the injured victims and send them to a Training From Hell where they shoot and throw grenades at each other until they are prepared to become domestic terrorists.
  • Ryuzaburo Sakata is the Pro-Gorgom leader of the EP Party. With the help of a psychiatrist, Sakata kidnaps artists and brainwashes them into becoming spies for Gorgom with RSD and hypnosis. Sakata teaches young musicians about the "Devil's Melody", a song that can damage a person's senses, ordering a girl to play the song in a public location. After stealing a prototype from a benevolent man, Sakata takes advantage of his political party's boy squad to make himself look like a peacemaker and spearheads a systematic Genocide from the Inside against the sickly and frail with a machine that supposedly cures their illnesses but slowly kills them instead.

Heisei Phase 1 Series

• Kamen Rider Kuuga: While the Gurongi Tribe is a race of Serial Killers, three of them stand out as among the worst of their kind:
  • The Gurongi lord, N-Daguva-Zeba, is a sadistic Blood Knight and The Social Darwinist who cares nothing for the lives of humans or his own kind. Upon being reawakened, Daguva releases his 200 Gurongi, slaughtering the archaeologists who found them. Restarting a brutal game in which the Gurongi hunt humans, Daguva kills over one hundred of his own kind for being too weak to take part in the killing game. When the titular Kamen Rider defeats one of his henchmen, Daguva ambushes him, mercilessly beating him and incinerating countless innocents before leaving. Continuing his systematic genocide, Daguva attempts to bring about "Ultimate Darkness", turning humans into twisted, vile creatures like himself and even after being fatally wounded by The Hero, dies Laughing Mad, hoping the latter will become as evil as himself.
  • Go-Jaraji-Da, the Porcupine Gurongi still stands as the standard to which other kaijin-of-the-week in Kamen Rider are compared to even years after he blighted television screens in Japan. Jaraji uses his upper-class privileges to choose the 90 teenage boys in Midorikawa High School's 10th grade as his targets for his game. Using super speed and poisonous darts that kills his victims from encephalitis within four days, Jaraji terrorizes and poisons all but one of his targets, condemning many of his victims to slow, brutal deaths and drives others to suicide. As those who commit suicide do not count to his Gegeru, Jaraji compensates by killing high-school boys belonging to other grades and numerous policemen. Most of the other Gurongi are either required to participate in the Gegeru or merely see the Gegeru as a necessary duty. Jaraji, on the other hand, commits his crimes precisely because he enjoys himself watching living beings suffer and coldly admits this to a family before closing in on one of his targets.
  • Go-Jaaza-Gi, the Shark Gurongi, is the only female member of the Gebageru subgroup and a Dirty Coward who stands in contrast to her battle-loving compatriots, choosing those who cannot fight back as her targets. Assuming the form of a well-dressed, glasses-wearing woman, Jaaza posts blogs on the internet to announce the massacres that she'll commit minutes prior to hunt for victims. To start her game, Jaaza infiltrated a plane and slaughtered the elderly passengers, forcing the pilot to send a distress call to the police before she killed him as well to make the plane crash; this incident alone had 244 casualties. After impaling Godai's shoulder with a harpoon, Jaaza planned on invading a cruise with 324 people on-board, most of which were children, intending on ending their lives simply because killing them would be "too easy".
• Kamen Rider Ryuki: In this battle of where There Can Be Only One, two Riders (aside from the previously mentioned Takeshi Asakura) stand out as particularly vile:
  • Jun Shibaura/Kamen Rider Gai is a rich, Machiavellian college student and a Psychopathic Manchild who sees people's lives as tools to satisfy him. Recreating the Rider Fight in the form of a computer game that would send subliminal messages to players, Shibaura convinced his own colleagues to participate, always recording the loser getting brutally killed in the process. Putting himself in the position of ORE Journal chief editor, Shibaura planned on spreading city-wide violence by sending his program to their subscribers. In his last act of malice, Shibaura kidnapped Yui to reunite the Riders in order to make a "Rider Party" where he could see them fighting each other in his own definition of the ultimate game. Brought back in 2019 as one of the six returning veterans to participate in the new Rider Fight, Shibaura leads an alliance of like-minded sociopaths to crush Shinji's opposition and develops an obsession for Tezuka, taking advantage of his fuzzy memories to become his lover, making him betray Shinji by feeding Ishida to Evildiver. To celebrate his victory, Shibaura stabs his friend to death and casually eats barbecue with the bloodied knife before sleeping with Tezuka, fantasizing about how killing his romantic partner would be a "passionate way of expressing our love".
  • Masashi Sudoh/Kamen Rider Scissors is a detective who uses his position to cover up his illegal acts. Asked for a larger share of the profits by his partner, Sudoh kills him and plasters him into the wall of his own shop to hide the evidence. When Shiro Kanzaki offers him an Advent Deck, Sudoh agrees in order to use the Contract Monster he's given, Volcancer, to feed it anyone who knows of his crimes, doing so to countless people who've come too close. He later attempts to kill a reporter inspecting his shop and Shinji Kido after he offers peace, along with anyone close to him to keep them quiet and hold Yui hostage from Shiro. With his crimes discovered, Sudoh follows it up by feeding two cops attempting to arrest him to Volcancer before he succumbs to the same fate as them. In spite of having little screentime, Sudoh was the first demonstration that some Riders were selfish people with only their own interests in mind, willing to stoop to absolute lows.
• Kamen Rider 555: In this Cyberpunk world that stands as one of the darkest series in the franchise, these select two stand out:
  • Kitazaki/Dragon Orphnoch is a Lucky Clover agent who cares more for his own enjoyment rather than the Master Race philosophy preached by Smart Brain. A sadistic teenager with the power to turn everything he touches into ash, Kitazaki, who lives solely for fighting and killing, sees the war between humans and Orphnochs as an opportunity to never feel bored again. Shortly before the events of the series, Kitazaki took part in a massacre that left several Ryusei students dead, killing Mari and Sawada himself. When in the presence of other Orphnochs, Kitazaki uses his abilities to physically hurt them, such as pressing his fist against their cheeks. After obtaining the Delta Gear, Kitazaki uses it to engage in brutal confrontations with other Riders, and tortures another Lucky Clover assassin when he tries to steal it from him. If the mission he is given is not fun enough, Kitazaki creates "games" to challenge the rest of the Lucky Clover, such as promising to slap other members in the arm if he kills their target first, knowing this would leave them without a limb. In one of his games, Kitazaki decides to kill their king, the Arch-Orphnoch, a being living inside the body of a little boy, just to prove his superiority, despite having the information that this would result in the extinction of his entire race.
  • Masahiko Minami is a xenophobic National Police Agency officer and human supremacist who leads an opposition against Orphnochs to purge all of them, living by his own sociopathic dilemma of using those who allow themselves to be used. Introduced stopping a police investigation, Minami recruits an innocent detective to spy on an Orphnoch, and orders his death when the man began sympathizing with Orphnochs. In his facility, Minami has an Orphnoch kept locked inside a glass box as his own guinea pig, conducting inhumane experiments to revert them back to human form. Making a deal with Smart Brain to have more subjects, Minami captures Yuka and electrocutes her, ignoring complaints that the operation could kill her, as he considers her a "worthless life" anyway. When she is saved by his prisoner, Minami promises that he is trying to work towards human and Orphnoch cooperation, but sets up a squad of heavily armed soldiers to eliminate Yuka, Kiba and Takumi, indirectly causing her death. When the laboratory is attacked by an enraged Kiba, Minami leaves his staff to die and escapes to save his own skin. When he's found and killed by Kiba, Minami spends his last moments laughing at his face and stating that the Orphnochs will never succeed. Existing solely to show that Humans Are the Real Monsters, Minami proved himself to be far more evil than many Orphnochs.
• Kamen Rider Blade: In the battle royale to become the dominant species, many competitors had good qualities, but these selected few only care about themselves and crossed the ultimate line in an attempt to achieve victory:
  • Hiroshi Tennouji creates the Battle Fight by releasing the Undead and manipulating his contracted Kamen Riders to take them out. As the battle progressed, he invented the Trials and the Titan Undead, all so he could buy himself time to create Kerberos, an artificial Undead with DNA from all 53 Undead that could surpass the Black Joker itself. Tennoji's invention kills the entire BOARD staff upon being born from the Stone of Sealing before he seals the artificial Undead to create a new Change Card. He uses the card to transform into Kerberos II before revealing his dream: to become the genetic template for a new world order, ruled by him.
  • Peacock Undead exemplifies how low Manipulative Bastards can go. As the first Category Jack Undead, he designed Rider System 3, a belt that allows the user to transform into Kamen Rider Leangle. Unfortunately, that same belt requires using an improperly sealed Ace card that contains the Spider Undead, meaning that its user would be mentally enslaved by the Undead (as later seen with Mutsuki). After designing the corrupted Rider System, he brainwashed many people that he was going to use as expendable slaves to create his "Ultimate Rider". When this plan failed, Isaka turns his attention to Sakuya Tachibana and attempts to retrieve him as a prototype user. Isaka knows about Tachibana's subconscious fear and takes advantage of it to curbstomp him. Isaka tricks his defeated opponent to getting addicted to Schuld Ketsner seaweed, lying that the aggression-inducing plant would eliminate fear. When Tachibana's girlfriend Sayoko notices her lover's addiction, Isaka smugly kills her for attempting to clean up her lover.
  • Shinmei/Wolf Undead is the third Category Jack and is, like his predecessor Isaka, a calculating scoundrel. Possessing the unique ability to revive human corpses as his minions and having infiltrated human society as an "Undead Hunter", Shinmei goes on random killing sprees and then sends his squad to eliminate his victims, hunting other Undead in the process. Pretending to be an ally of BOARD, Shinmei completes the Black Fang, a motorbike which he had stolen from the company, with the help of Kenzaki and Tachibana, massacring his own crew afterwards and intending on using the motorbike to seal every other Undead and become the strongest.
• Kamen Rider Kabuto: In the war between the ZECT paramilitary armed forces and the intergalactic invaders known as the Worms, these three show themselves to be the pinnacle of evil in the work:
  • Masato Mishima, the second-in-command of ZECT, is their Token Evil Teammate. In the past, Mishima captured the young boy that would become Dark Kabuto and performed horrendous experiments on him to unlock the power of the Hyper Zecter, keeping him as a prisoner for years inside a ZECT facility in Area X. Assigned to oversee the development of the Gatack Zecter, Mishima wastes no time in sacrificing the lives of his own soldiers to see who is worthy of its power. Mishima allies himself with the Worms to stop the independent non-ZECT Riders, framing Daisuke for the murder of a rival makeup artist and later sending an agent whom he forced to eat nothing but dry boiled rice for the last seven years of her life to pose as a cadet to get closer to Tendou in a plot to assassinate him. Taking part in the AM Bomb operation, Mishima is disappointed in his superior for attempting to save the civilians that were made hostage by the Worms in Area C3, informing Arata that if he fails the negotiation, he'll just nuke the entire district. After the existence of Worms is announced to the world, Mishima turns himself into a Native and conspires to do the same with the rest of the world by usurping the position of general and, just so he doesn't get to lose his status after all the Worms have been exterminated, manipulating the population into wearing a pendant that detects Worms, but, unbeknownst to them, also converts those wearing it into Natives.
  • Reiji Nogi/Cassis Worm is a field leader of the Worms' army who, despite being introduced in the last episodes, proved himself to be the worst of his race. An open cannibal, Nogi follows the philosophy that he must devour the weak by absorbing his own subordinates. Making his appearance known by destroying the peaceful Natives that were being escorted by ZECT, Nogi leads the counterattack against ZECT during the AM Bomb operation and makes the entire Area C3 fall under control of the Worms, promising to execute civilians if ZECT doesn't give the anti-mimicry device to him. With the Worms attacking four different sections of the city at the same time, Nogi directly participates in weakening ZECT's defenses by killing a platoon that was stationed at one of the sites to stop the Worms from continuing their rampage. Going to Shibuya, Nogi brings the Worms to slaughter the soldiers at Area Z, massacring all of those that were guarding the place from him except for the last line of defense, who almost committed mass suicide by nuking the place with them inside to prevent Nogi from stealing the Masked Rider System. After failing to recruit Dark Kabuto to his side, Nogi was ultimately responsible for Tsurugi's Suicide by Cop by making him remember that he is a Worm.
  • The unnamed principal of Jyuka Tendou's high school from the School's Ghost Story Filler Arc is a human who willingly collaborates with the Worms all for the sake of pride and fame. Discovering the existence of the Worms after they replaced his choir group, the principal decided to take advantage of their superior abilities by forming a pact with them to replace his own students and make the Worms win at competitions instead of risking to lose with his human students. Sealing the Worms inside an abandoned part of the school that is covered by a mirror, the principal allowed a rumor to spread about the "cursed mirror" that grants the wish of desperate students but also makes them disappear, resulting in an entire basketball team going missing. After Tendou and ZECT uncovered the truth behind the mirror, the principal refused to accept responsibility and blamed the students for wanting their wishes granted, telling Tendou that his own sister was the last person to have approached the mirror with a wish, which led to the Worms going after a bus filled with innocent students.
• Kamen Rider Den-O: The Wolf Imagin is a psychotic berserker who ranks amongst the worst in Kai's army. Forging a contract with Yuka Sawada, who wished to have memories of her years in high school, Wolf began vaporizing schoolgirls and giving their possessions to Yuka, all while mocking her for having a boring wish. Going to the past, Wolf wastes no time in causing even more chaos. Frustrated by the lack of orders, Wolf goes on a rampage, collapsing entire buildings and killing countless civilians
• Kamen Rider Kiva: While the Fangire race are the major antagonists in the series, there are 4 specific members who crossed the ultimate lines:
  • Rook/Lion Fangire, who spends all of his free time making up "games" for himself that generally go along the lines of, "Let's see if I can kill X amount of people wearing Y in Z amount of time." He has a lot of free time. To say nothing of the fact that he is responsible for the near-genocide of, at the very least, the Wolfen, as well as the death of Yuri Aso's mother, Akane. His "death" at Yuri's hands (and his total annihilation at the hands of Megumi) were quite karmic indeed.
  • Tohru Miyake/Rhino Fangire was a rather nasty bastard. He strung along people trying to make it in the show business, only to kill them and take a prized possession of them. Even Wataru, who has been known for trying to find the good in Fangires, found his actions unforgivable.
  • The ruthless King/Bat Fangire was pretty monstrous on a more personal level - forcing Jiro (the last of the aforementioned Wolfen), Ramon (the last of the Mermen), and Riki (the last of the Franken) to become Empathic Weapons and developing a full-blown hate-on for Otoya, up to the point of threatening his own infant son's life if his wife sees Otoya again...the same woman whom he told was not worth killing because he had no feelings for her. The King's actions were so horrible that Kivat II, who is meant to be the King's loyal Transformation Trinket, is so horrified by King's threat to murder his own son that he pulls a Heel Face Turn to let Otoya become Dark Kiva to defeat him.
  • Bishop/Swallowtail Fangire is the King's calm but psychopathic right-hand man. A firm believer in the superiority of Fangires, Bishop informed the King of his wife's love for a human, resulting in Maya having her powers taken away from her. Trying to force Mio into embracing her fate as the new Queen, Bishop burns a Fangire in front of her when she refuses to kill him for having loved a human, later telling her that she must kill her Love Interest if she wants to be a true Queen. Under Taiga's orders, Bishop uses his powers to awaken Wataru's Fangire blood, almost making him murder his own friends. Seeing Mio as a failure, Bishop assassinates her and pins the blame on Wataru, fully intending on leaving him depressed. Proudly confessing his crimes to Taiga, Bishop is kicked out of the Checkmate Four and uses a magical crystal ball to drain the souls of multiple people. Planning on bringing the previous King back, Bishop revives the defeated Fangires and orders them to murder every human they come across, sacrificing his own soul to complete the ritual just so he could become one with the King and "destroy everything".
• Kamen Rider Decade:
  • Momose/Tiger Orphnoch, the prideful leader of the new Lucky Clover in the World of Faiz, is introduced as a member of a gang of bullies studying at Smart Brain High School who is quickly revealed to be a budding psychopath. Having orchestrated a series of attacks targeting other students, Momose tries to kill Takumi's best friend in front of him and orders his comrades to indiscriminately kill numerous students while he could watch and mock the victims. Not satisfied with the initial massacre, Momose gathers the survivors in a circle for them to be executed one by one, informing them that if they are lucky, they could be turned into Orphnoch.
  • Otoya Kurenai is King's substitute in the World of Negatives, possessing not only all of his Fantastic Racism, but also a charismatic personality to hide the fact that he is a cold-hearted, scheming dictator. As the commander of the Dark Riders, Otoya annihilated more than half of humanity in a genocide, and leads the extermination of survivor camps, while also abusing those who defy him. Seeking to make Tsukasa his successor, Otoya tries to corrupt him into abandoning his journey and accepting the nature of his oppressive world.
  • Apollo Geist in this incarnation drains the life out of people to extend his own and has been working to converge the various worlds to facilitate Dai-Shocker's invasion of them, eventually becoming powerful enough to wipe entire worlds from existence, which he does with glee.

Heisei Phase 2 Series

• Kamen Rider Double:
  • Makoto Uesugi/Jewel Dopant is a vain male model obsessed with perfection, with a history of destroying anything he decided didn't meet his standards. Having fallen in love with his female best friend Rui Jojima, Makoto was furious to learn she and their other best friend Satoru Takeda fell in love with each other before he could confess; Makoto responded by purchasing the Jewel Memory and turning Satoru into a diamond ring to force Rui to be his scapegoat as, realizing there's no such thing as a perfect person, he decided to turn various women into perfect diamonds. When Rui was able to get the Narumi Detective Agency involved, Makoto played the victim to divert all suspicion to Rui before setting up her death to close the case and flee Futo to turn more women into diamonds. When Rui calls him out on his actions after being saved by Terui, Makoto responds with pride in his actions and standards before attempting to throw the diamondized Satoru into the sea to spite her.
  • Jun Kazu/Utopia Dopant. Now you may ask yourself, "What's so bad about Utopia?" First of all, he has every power imaginable by turning earth into Utopia, which he manages by stealing a person's necessary emotions, like hope and happiness. He then proves how far he's willing to go by setting Accel on fire to the point of causing him to detransform and still be on fire! He then proceeds to steal the faces of everyone in the supporting and main cast except for Wakana, Shoutaro, Saeko, Phillip, and Terui. He then kills the woman he loves. And it takes a nuke and Phillip's death to kill him!
  • Doctor Shinkuro Isaka/Weather Dopant killed Terui's family, modifies Gaia Memories to kill their users so that he can take their power for himself, and is able to use Gaia Memories via direct insertion without any ill effects (typically, repeated use of Gaia Memories via direct insertion warps the user's mind, which shows that Isaka didn't have far to fall). He then tries to get Saeko to kill her own father and take control of the Museum, but winds up getting Hoist by His Own Petard when all of the Gaia Memories he absorbed essentially destroy him from within upon Memory Break.
  • All of the above are blown out of the water with a nuke by Dr. Prospect from W Returns: Eternal. This man took people from all over the world (their words implying they were kidnaped) to make them into, in his own words, "lab rats" for his Quark Project, giving them psychic powers. The fact that, when he arrives on the scene, every one these people with awesome Psychic Powers is quaking in fear of him shows how horrifically he must have treated them. But that is nothing compared to his Heaven's Fall plan. This is a plan so horrible that the previously mentioned Utopia Dopant considered it a brutal act! He would blast the area with an electric pulse, killing anyone that has not lived up to his standards for the project, referring to it as "cleaning out the test pool". When Daido ruins that plan, he reveals that was merciful compared to what happens if they try to escape. The eyes he implanted on them to watch them kill them when they leave his compound. And as Katsumi is in shock over the slaughter of the entire village he'd tried to save, Dr. Prospect is laughing his head off at the fact he'd just slaughtered a village of innocent people! His actions are so horrific that it drives Katsumi insane! What this monster put Daido Katsumi through was so terrible and so horrific that it actually serves as a valid Freudian Excuse for Katsumi and also means Prospect was responsible for everything that happened in the movie! There's a special place in Hell for this sicko, and Katsumi was more than happy to send him there.
• Kamen Rider OOO:
  • Dr. Kiyoto Maki is an interesting version of this as he didn't start out a monster but grew into one through character growth. He does some truly horrible things early on, like helping a Mad Bomber who is hosting one of Mezool's Yummy carry out his attacks to see the Yummy grow, not caring who dies in the process. When the swarm of Yummy hatches, he responds by locking his workers inside with them to see what would happen. Predictably, they slaughter the workers, which Maki doesn't care about. He then one-ups himself by joining forces with the aforementioned Kazari. Later, it seems like he might find redemption when his dead sister is brought up. However, it turns out what he came to believe were false memories and he actually burned his sister to death in her sleep just because she was getting married and would have abandoned him. After he realizes this, he loses all the humanity he had left and willingly sides with Kazari to attempt to destroy the world. This is where he flies past the Moral Event Horizon by absorbing five Purple Core Medals to begin transforming into a Greeed himself. His Yummy so far have been Omnicidal Maniacs and a monster who tears people's dreams apart, leaving them in a coma as a result. What's his reaction to this? He finds it "interesting" and justifies it as For Science! He's just been getting worse and worse since then. Kazari finds out too late that Maki was Eviler Than Thou when Maki impales him and rips all his cores out of him, leaving him to die a slow painful (though admittingly well deserved) death. He also gives two of his own Cores to Eiji, to accelerate Eiji's greeedification. Finally, he tosses the remaining Core Medals from the other Greeed into Uva to forcibly set his ultimate plan into motion--much to Uva's horror.
  • Kazari, the Feline Greeed, is a fine example of how a Magnificent Bastard can also be a Complete Monster. Of the five original Greeed, he has by far the most horrifying way of making Yummy, implanting them in their host and controlling their body like parasites; in some cases, the host is conscious the entire time. In the end, they're consumed by it and trapped inside, fully aware of what's happening. If that weren't bad enough, Kazari's actual actions are much worse. He used Mezool, the Team Mom of the Greeed, and Gamel, a Man Child who really doesn't know better, as lab mice to see what would happen if a Greeed absorbs Core Medals that aren't their own and wasn't the least bit disturbed when this proved fatal for them both. In fact, he took advantage of it to assimilate their Cores and get even stronger. After that, he begins raising Lost Ankh as his own personal Tyke Bomb and actively helps Dr.Maki try to destroy the world. And he did all this with a sick smile on his face (well, in human form, anyway). He's so evil that even his own kind doesn't care about his demise.
  • Another Complete Monster is the original Kamen Rider OOO. An evil king described as "desire incarnate", his goal was to conquer the world and become an immortal god. To achieve this goal, he had five fully sentient organisms created for the sole purpose of killing them off to reach his goal. He then stabs Ankh, the only Greeed who willingly works for him, in the back for his Core Medals. Worth noting is that he's so power obsessed that he's called Selfish Evil by a living incarnation of human greed! His own greed ultimately spells his end when he can't handle the power he finally absorbed and is killed by it.
• Kamen Rider Fourze:
  • Hiroki Makise/Pyxis Zodiarts was a psychopathic stalker who kept a journal of the girls he was stalking and sent loads of messages, love letters and gifts to these girls, but what really pushes him past the Moral Event Horizon was when he blew up the Rabbit Hutch locker and rubbed it in that Kengo would be left there to die all so he could see Yuki Jojima, the girl he was currently crushing on, cry. For a bus full of girls who found him (justifiably) creepy, his plan was to use his Zodiarts power to manipulate the bus to drive itself off a bridge killing all of them! The sheer joy he had causing these problems was staggering, seeing as how other Zodiarts have at least some sort of sympathetic reason for becoming Monsters of the Week Makise's excuse is cold blooded and sadistic revenge.
  • Kijima/Pegasus Zodiarts/Cancer Zodiarts is a Smug Snake who became a Zodiarts because the new teacher confiscated his fan and he decides to frame her by imitating martial arts moves. He also likes to rip out peoples souls by putting them into a "Comedy in Hell" routine; if you make him laugh, you get a Zodiarts Switch and if not, he steals your soul! The worst part of it was that he was doing all of this with a sick cheery smile on his little Troll face, and he gleefully adressed it as if it were everyday business, these were his fellow classmates mind you and he did this to innocent people willfully like The Sociopath he's known for being. He got what was coming to him in Episode 28 by Kamen Rider Meteor and Libra Zodiarts.
  • Yamada/Aries Zodiarts was transferred around the same time Ryusei came to Amanogawa and in that amount of time, he's the undisputed king of Subaruboshi high. He forces the whole school (teachers included) in his little play like world where everyone is graded on their performances. If they did bad jobs, he would them into a permanent sleep. He even makes a Deal with the Devil with Meteor, reviving Jiro if Meteor killed Fourze and he follows up on his deal. Then he decides to do a play called "School War" which has the Kamen Rider Club killing students before deciding to reverse the roles and have the Kamen Rider Club being tied up to poles and killed. Thankfully, Gentaro gets revived and kicks his ass so badly that he gets sent into a coma.
• Kamen Rider Wizard: Even in a series where the villains forcefully tried to turn humans into Phantoms by making them give into despair, a select few stand out as much worse than the others:
  • Phoenix stands out even among the Phantoms as a complete psychopath who will go to horrific lengths in order to make Gates to create more phantoms. His methods involve beating a lady just so her child would give into despair; he later breaks into a hospital and randomly attacks innocent people, including patients who have no connection to the Victim of the Week at all. Even his compatriot Medusa is frightened of his brutal tendencies since he has gone as far as to kill a Gate before the corresponding Phantom can manifest. His sadistic tendencies are so fierce that his boss Wiseman kept him to an observatory role at first rather than being allowed to directly intervene for fear of him going out of control.
  • Sora Takigawa/Gremlin became a misogynistic Serial Killer after murdering his girlfriend for breaking up with him and than started to target other women matching her description before being made into a Phantom. Unlike most Phantoms who lose all aspect of their personality, Gremlin retains Sora's sadistic desire to hunt women. Pretending to care about protecting the Gate, Sora reveals he really just wanted to use her to indulge in his sadistic fantasies and then tries to kill her. Killing his boss, Wiseman, to gain power, Sora also kills Haruto Soma's Love Interest to take her Philosopher's Stone. Using it to rampage through Tokyo, Sora attempts to spread enough despair to turn all Gates into violent Phantoms while killing all the remaining normal humans in the city.
  • The Legion Phantom has the power to invade and destroy a person’s Underworld, which he abuses to satisfy his love of destruction. Seeking anyone altruistic enough for him to consider "Beautiful"—children included—Legion puts them in a catatonic state, a process shown to be extremely traumatic. With no loyalty to anything save his lust for destroying good people, Legion made an impression despite his limited screen time.
• Kamen Rider Gaim: In a series that takes the franchise back to its Darker and Edgier roots, there are two heinous villains who cross the ultimate lines:
  • Professor Ryoma Sengoku/Kamen Rider Duke is a researcher for the Yggdrasill Corporation who created most of the Armored Rider gears. Unlike his comrade Takatora Kureshima, Ryoma does not care about saving humanity and secretly desires the Helheim Forest to invade so he can become a god with its Forbidden Fruit, not caring about the billions of deaths it would cause. When Takatora's altruism get in the way of his plans, Ryoma coldly attempts to murder him before abandoning everyone else in Zawame City to die when the Overlord Inves invade. Ryoma later makes a deal with Mitsuzane Kureshima to save Mai's life if he kills Kouta Kazuraba, only for him to murder Mai to get the Forbidden Fruit inside of her, which he gleefully admits to Mitsuzane when he accomplishes the task. Supplemental material reveals Ryoma once agreed to help Kagiomi Shizumiya with the human experiments that ultimately led to the destruction of the Torkia Republic.
  • Redyue is the worst of the diabolical Overlord Inves. As a vile, selfish, and Manipulative Bitch, she brags about having killed her entire family and corrupts Mitsuzane Kureshima into becoming her puppet, using him to obtain human subjects for a machine that would revive the dead. She aggravates the humans into launching missiles, thereby forcing her superior Roshuo to redirect the missiles to America and to declare war against humanity. She is also not above Mind Rape, as seen when she tries to mentally break Kouta Kazuraba by portraying him in a hallucination as an Inves being attacked by his former mentor Yuya. Moreover, Redyue has a sickening obsession over backstabbing and killing those close to her, as seen when she ruthlessly kills Roshuo after the latter defeats Kouta and Kaito Kumon. While the rest of her fellow Overlords, except for Roshuo, were definitely evil themselves, Redyue stands out for her willingness to use any means necessary to play mind games with, and to commit genocide against, humanity, simply For the Evulz.
• Kamen Rider Drive:
  • Professor Tenjuro Banno/Kamen Rider Gold Drive is an egotistical, sociopathic scientist with a god complex. After being refused funding by a potential investor, Banno has one of his Roidmude androids, Roidmude 002/Heart, assume the man's form and tortures it to take out his anger. Inserting negative emotions into the Roidmudes out of spite against his former partner, Banno's abuse leads to them becoming violently unstable, going on to rampage and kill countless people. Even after his death, Banno turns himself into a Virtual Ghost, manipulating his own son into releasing his spirit before trying to kill him. Banno manipulates Medic into being operated on, leaving her a puppet loyal to him and forces Heart to serve him, lying that he will restore Medic if he does so. Ultimately planning to digitize the entire world, Banno intends to only give robotic bodies to those who will bow to him.
  • 010 Paint Roidmude is a Mad Artist whose sadism disturbs even other Roidmudes. During the Global Freeze, Paint personally attacked Kiriko, turning her arm into data until she was saved by Proto-Drive, an event which traumatized her. Six months later, Paint assumed the identity of a gallery owner whom he had trapped inside a painting, and with the assistance of his apprentice, did the same thing to several women who wandered near the gallery, all while they were aware of their situation but unable to escape. Realizing that Kiriko is investigating the serial kidnappings, Paint triggered her post-traumatic stress by attacking her once again. Using Mashin Chaser as a distraction, Paint planned on fleeing to another area so he could find a new hunting ground, but not before he tried to trap Kiriko in a painting, seeking to immortalize her expression of pure and sheer terror.
• Kamen Rider Ex-Aid: Masamune Dan/Kamen Rider Cronus is the first CEO of Genm Corp., a game company he uses to upload people into the digital world. First appearing as a victim of his son, Kuroto's, misdeeds, it is revealed that Masamune willingly allowed his child to infect and kill countless people for his own plans. After taking charge of the deadly video game, Kamen Rider Chronicle, Masamune tricks people into playing the game, collecting their data once they are in it to control their lives. Destroying any who oppose him, Masamune also uses his control of data to delete a woman when her lover refuses to murder a heavily injured Taiga for Masamune. Reprogramming the Final Boss of Chronicle so it will digitize the entire world, Masamune seeks to control everyone's life. When offered the chance for redemption, Masamune kills himself, making it impossible to revive those who died in his game, controlling and spiteful to the end.
• Kamen Rider Build: In this tale of creation versus destruction that stands as possibly the darkest series of the Heisei era, this duo are the most vile:
  • Evolto/Kamen Rider Evol, the true mastermind behind the problems faced by the heroes, is an entity seeking to create a "new world" by devouring everything in the universe, leaving only himself. Destroying planets alongside his people, the Blood Tribe, Evolto wiped out many civilizations before being stopped on Mars by the surviving Martian Queen Vernage. Possessing an astronaut and rendering him aware but unable to do anything, Evolto goes to the Earth and causes the Skywall Disaster that killed countless innocents and split Japan into three states. Under the alias "Blood Stalk", Evolto corrupts Gentoku Himuro by preying on his mind and killing his best friend and founds Faust with him and scientist Takumi Katsuragi to carry out painful experiments on kidnapped people to turn them into Smash. When Katsuragi discovers his alien origins and turns against him, Evolto mind wipes him, kills an innocent man to swap his face with him, and renames him "Sento Kiryu" so he can keep using him. Desiring Ryuga Banjo, whom he corrupted with his DNA when he was only an infant, as his new host, Evolto had Ryuga's fiancée, fatally transformed into a "Smash", to increase Ryuga's raise Hazard Level by increasing his rage. Inciting a war between the three states of Japan, Evolto painfully experiments on Gentoku to turn him into a weapon and takes over Sento's body, keeping his personality around so he can make him watch as he slaughters his friends. He later betrays Namba and challenges the Kamen Riders to a final battle where they will have to reach the top of the Pandora Tower, destroying a section of Japan for every ten minutes they don't make it. Achieving his ultimate form, Evolto summons a Black Hole to consume the Earth but destroys it slowly so he can gaze at the despair on the heroes' faces for longer.
  • Juzaburo Namba is the greedy CEO of Namba Heavy Industries and Evolto's collaborator. Profiting off the Skywall Incident, Namba was responsible for converting children into his brainwashed, suicidal Child Soldiers and turning Seito into his Puppet State. Taking part in the creation of Faust, Namba sponsored the criminal organization with the intention of sparking a conflict between the nations to fill his pockets. Planning on making a weapon stronger than a nuke with the Pandora Box's energy to sell to the highest bidder, Namba tortures the mentally-broken Gentoku Himuro until he is ready to become his own Kamen Rider, implanting a chip in his body that would kill him if he disobeyed his orders. Deciding to reunify Japan into a world superpower under his law to give birth to an "immortal Namba empire", Namba engineers a massive and destructive military coup to conquer the country and the world, starting by taking Prime Minister Tajimi into custody, assassinating Prime Minister Mido and then sending his troops to invade Touto to be assimilated by force. Side material expands even more on his atrocities, as he had imprisoned Gentoku in an annexed concentration camp for failed Faust experiments, a place where he was regularly beaten, and in one occasion, suffered an attempted rape at the hands of another prisoner. At some point, Namba had employed Kaisei Mogami and allowed him to work on the Enigma, indirectly killing even more people and almost causing the destruction of two worlds.
• Kamen Rider Zi-O: In this battle across time to become a king which marks the end of the Heisei era, these stand out as vile contenders for that throne:
  • Sougo Tokiwa/Kamen Rider Oma Zi-O from the year 2068 is the Demon King of Time of the future who rules over the world in a totalitarian dictatorship. Once an eccentric, lonely but seemingly harmless underachiever who dreamed of becoming a king, Sougo rose to become the most powerful Kamen Rider in history and used his newfound powers to establish a so-called military rule by causing worldwide destruction, killing billions and turning earth into a desolate wasteland for him to control what remained of humanity. In 2068, Sougo's actions force the survivors to live in ghettos, and he personally annihilates the resistance that was formed to combat him, recruiting one of their captains as his own fanatical prophet and sending him back to the past to serve as a mentor to the younger Sougo, motivating him to follow his same path. Revealing that the true extent of his power could destroy time and space, Sougo openly desires to see which timeline his past-self would destroy and how he would go on about it.
  • Swartz/Another Decade, head of the Time Jackers, is a sociopathic prince from another timeline. Enraged that his sister would inherit the throne over him, Swartz set up a bus crash to kill multiple adults and brainwash children to see who was worthy to become the powerful Oma Zi-O as a vital part of his plan. Manipulating others by turning them into monstrous Another Riders to spread destruction, Swartz is happy to murder any heroes in his way as he seeks his ultimate goal: to merge the timelines into one and then destroy them all, killing every being in the multiverse, so he may become a hero to his own world and rule it himself. When he is exposed, he happily tries to eliminate any of his old allies, even trying to murder his own sister.
  • Asura/Another Gaim is a member of Team Baron who, after being kicked out by Kaito Kumon, is transformed into an Another Rider by Swartz and used his power to always be on the top. Asura sends any who question him or get in his way like Kaito and Geiz Myōkōin-—which he did to stop Geiz from saving civilians attacked by Ora and Swartz—-to an artificial version of the eldritch Helheim Forest, isolating them for five years until they were finally released. In this eldritch and visceral forest, Asura has monsters that will hunt his victims down, caring for only himself and his dreams.

Reiwa Series

• Kamen Rider Zero-One: Azu is the only member of MetsubouJinrai.net without redeeming qualities and their worst Psycho Supporter. A jovial but sociopathic Humagear resembling Hiden Intelligence's Izu, Azu doesn't care for the supremacist ideology of the extremists, worshipping Ark and starting conflicts for her own amusement. Meticulously collecting data to revive Ark, Azu succeeds in bringing the malicious AI back to Japan, leading to more terrorist attacks and countless explosions across the entire city. After Ark's defeat, Azu manipulates Aruto and Horobi to replace it and trigger a Robot War that will inevitably result in both sides losing, seeking to distribute the power of Ark among the population and using the genocidal Kamen Rider Eden as her backup plan to ensure a massive number of casualties.

Spinoffs

• Kamen Rider Dragon Knight: General Xaviax/Kamen Rider Wrath is an arrogant alien warlord and the one behind all the tragedies throughout the series. Originating from the planet of Karsh, Xaviax devastated his own planet with a long-lasting civil war and decided to enslave civilizations from other planets, starting with Ventara. Having badly injured his former ally Eubulon and vented nine of the original Ventaran riders, Xaviax saw Earth as his next target. Kidnapping humans and leaving them in coma, Xaviax manipulated a group of people into becoming riders, taking advantage of Kit's love for his father, one of his victims. Xaviax's ultimate goal was to not only make humanity his next victim, but to hunt for the Ventaran riders who had escaped from him, especially Len. Succeeding in bringing riders to his side, Xaviax orders his right-hand man to vent the agents whom he considers to be loose canons, and was indifferent to his venting at the hands of a furious Len, possessing the body of a comatose patient to use him as his new puppet. Failing to achieve his goals, Xaviax made a final attempt to manipulate the riders before his death. While seemingly caring for his planet, his superficial charm, extreme methods and pride towards his own cruelty reveal his noble intentions as the empty excuses of an unfeeling tyrant with a superiority complex and a self-proclaimed evildoer.
• Kamen Rider Amazons: In a series that runs on Grey and Gray Morality scale, these three characters stand out as the most vile:
  • Takaaki Tenjo is the Chairman of Nozama Pharmacy, helping develop the Amazonz, man-eating monsters that only have so long to live before becoming savage monsters. After their creation, Tenjo released the Amazonz from their lab to create an ecosystem where everyone will have to kill to survive. He and the other Nozama executives create the Nozama Protection Service (NPS) to deal with these beasts, but will gladly keep thousands alive in secret to ensure the Amazon Cells stay in their property, even creating Amazon Sigma from one of the dead members of the NPS to succeed the other Amazons. Tenjo is later disgusted with Sigma, not out of standards, but because he lacks the need to kill to survive. By the series's end, Nozama Pharmacy is out of business and countless Amazons are left roaming in the world to kill all around them, and when Tenjo is confronted by his co-workers for his deeds, he expresses nothing but utter delight. In a series that shows a tragic side to both heroes and man-eating monsters alike without either side winning in the end, Tenjo stood out as a being of unrepentant evil who, despite Nozama getting shut down, ultimately ended up getting all that he wanted.
  • Initially appearing to be a fitness-obsessed jerk, Soji Shitashimo is actually a Serial Killer of women who uses his junkyard as a dumping ground. Upon realizing that he is being suspected for murdering another woman, he tries to kill two agents sent to investigate him, Nozomi and Mamoru, by burning them alive, and when that fails, he decides to torture them instead, binding them with chains and forcing one to watch as he beats the other with a pipe, mocking Mamoru for being an Amazon as he does so and telling him that he can only feel alive when beating something until it is "bloody broken and unable to move". Annoyed by Nozomi's attempts of ordering Mamoru to break the chains, he proceeds to savagely beat her in front of Mamoru with his own fists until her face is a bloodied mess, laughing at her suffering like a child playing with a toy. Unlike the Amazonz, Shitashimo is merely a vicious sociopath who enjoys killing innocent women simply because he can.
  • The Elephant Amazon is the most repulsive New-Type to be investigated by the 4C. Using his clinic as a front to find unsuspecting victims, Elephant's method of killing his prey consists of inserting a long proboscis into the victim's ear and dissolve the brain while they are still conscious, having done this to four people in just one week. After drinking the brain of a woman and leaving her to convulse, Elephant killed a random man, before trying to do the same to a woman who found the body, excitingly calling her his next patient. A callous sadist who gladly accepted his nature, Elephant served as a reminder that not every Amazon tried to contain the craving for human flesh.

Kamen Rider Films

• Shin Kamen Rider Prologue: In one of the darkest entries in the franchise, these two are the most vile characters:
  • Iwao Himuro is the paranoid head of the ISS. An uncaring, heartless Bad Boss to his employees, Himuro considers those who refuse to cooperate with his projects as his own enemies, and has them either assassinated or imprisoned. Using his facility as a front for human experimentation, Himuro plans on obtaining financial gain through the mass production of super soldiers to be sold to the military industry. Forcing Shin's father to continue the research after having his former partner "resigned", Himuro denies his permission to not get his son involved, explaining that it was "too late for that". Armed with a submachine gun, Himuro guns down Ai, Shin's pregnant girlfriend, when she takes the bullet for him.
  • Giichi Onizuka/Onizuka Rider is one of Himuro's top scientists and secretly a misanthropic Serial Killer. Harboring an agenda of his own, Onizuka sabotages an experiment, altering both his and Shin's DNA, seeking to create an army of human-grasshopper hybrids to overthrow humanity, with him as their ruler. He wants Shin to be his first recruit, once trying to convince him into embracing his violent side. As a Cyborg Soldier Level 3, Onizuka regularly commits murders around the city For the Evulz, primarily targeting lone women. Introduced brutally killing a woman in the middle of the night, Onizuka proceeds to cut the throats of two undercover police officers investigating the slayings, and slaughters the cops who had arrived at the scene. When his secret lab is invaded by the CIA, Onizuka nearly kills the entire squadron, and tries to repeat this when he is indirectly released from containment by a group of agents.
• Kamen Rider Agito: JGSDF Captain Risa Fukami of Project G4 is a dangerous combination of incompetence and indifference. An officer belonging to the GA division, Risa was in charge of an educational facility that exploited the abilities of psychic orphans. When the high levels of ESP attracted the attention of the Ant Lords, Risa merely saw the massacre as a failed experiment. Stealing information from the G3 Unit after being assigned to work with them, Risa completes the lethal G4 System and equips suicidal volunteers with it until she can find a way for it to be mass-produced, killing some of her own soldiers in the period of two months. After kidnapping Mana Kazaya, Risa connects her to a machine that absorbs her powers and gives them to the G4 System. Realizing that she had brought the Ant Lords to her base to kill even more people, Risa cowardly uses some of her soldiers as human shields, willing to sacrifice the lives of others even in the face of death.
• Kamen Rider 555: Paradise Lost: Leo/Kamen Rider Psyga, the Lion Orphnoch from this alternate continuity, is a Sociopathic Soldier placed under supervision of Murakami who is feared by humans and Orphnoch alike. A foreign who arrived in Japan to help with Smart Brain's cause, Leo was given the Psyga Gear after having found an extremely injured Murakami and demanding an Emperor Belt for himself, or else he would leave him to die. Leo joined Smart Brain's paramilitary solely to kill humans and have a chance to fight with other Orphnoch, leading the Riotroopers in the genocidal campaign against the human population. Introduced murdering three members of his own race with no hesitation, Leo participates in attacks against the Human Liberation Army at their sanctuary, personally killing Kusaka and leaving several civilians dead or injured, later taking the opportunity to bomb the place. Shortly after kidnapping Mari, Leo tried to stop Takumi from saving her, intending on having her executed on live television.
• Kamen Rider Blade: Junichi Shimura/Kamen Rider Glaive is the real identity of the Albino Joker, the Evil Counterpart to both Kazuma Kenzaki and Hajime Aikawa. Joining BOARD as the replacement for Kamen Rider Blade, Shimura became the team leader of the Ace Riders and used them to further his own goals, starting by killing the president of BOARD and then releasing half of the Undeads, allowing them to massacre humans just to seal them again as part of a ritual that would grant him ultimate power, disposing of his two subordinates after they had served their purpose. Sacrificing Amane's life energy to have control over an Eldritch Abomination, Shimura was an ambitious monster whose need for power knew no limits.
• Kamen Rider Kabuto: Issei Kurosaki/Kamen Rider Caucasus is ZECT's legendary Sociopathic Soldier and an eccentric thug who views strenght as beauty. Hired to destroy Neo-ZECT troops and help with the Jacob's Ladder project, Kurosaki becomes notorious for his enormous bodycount and habit of leaving roses on his victims' corpses. After executing Neo-ZECT leader Hidenari Oda, Kurosaki joins ZECT's inner circle in a conspiracy to annihilate humanity with a second meteor filled with dormant Worm eggs. When confronted by Tendou as to why he would let the Worms rule earth, Kurosaki confesses to not caring for the lives of both humans and Worms, merely wishing to satisfy his Darwinistic philosophy. Severely injuring renegade ZECT agent Arata Kagami in a space station, Kurosaki breaks the window of his escape pod out of spite, leaving him to freeze and suffocate to death.
• Kamen Rider Den-O: Gaoh/Kamen Rider Gaoh is an infamous time criminal who specializes in stealing Time Trains, and is the leader of his own gang of renegade Imagin to further his selfish goals, wishing nothing more than the destruction of time itself simply because he grew bored of it. After invading the DenLiner and taking its passengers as hostages, Gaoh goes back in time and obtains the GaohLiner, destroying an entire village as "practice". Travelling to the day when Ryotaro was born, Gaoh forces him to watch as he erases the city and its people from time, turning the place into a desolated wasteland and planning on repeating this process with the entire world.
• Kamen Rider Kiva: Arc/Kamen Rider Arc is the ancient ruler of the Legendorga and a mortal enemy to all the other Demon Races for his genocidal behavior. Countless years after being sealed within a coffin by the first Kiva, Arc invaded the body of death row inmate Takashi Sugimura when he accidentally found his coffin, preventing him from aging or getting executed for 22 years. In 2008, Arc helped Sugimura in breaking out of prison by releasing an energy blast that killed all the officers around him. Reunited with his loyal subordinates, Arc places Sugimura in a catatonic state until he's fully revived within him, resuming his role as the lord of the Legendorga and planning on annihilating humanity. Using the power of the Mummy Legendorga to enslave humans en masse and start a Zombie Apocalypse, Arc magically reproduces the screams of his victims with his own instruments to enjoy their suffering. When Wataru finally reaches Arc, he forcibly baptizes Wataru into a Half-Fangire Half-Legendorga creature to make him his own pet as a more sadistic way to end Kiva's line, ordering Wataru to murder his own father.
• Kamen Rider Decade: Nobuhiko Tsukikage is a slimy member of Dai-Shocker who, through treachery and manipulation, became their new Great Leader. Acting as the seemingly loyal butler of the Kadoya family, Tsukikage's real identity is that of Shadow Moon from another reality where he lacks all of his original counterpart's sympathetic qualities. Keeping a close eye on Sayo Kadoya for possessing the source of Dai-Shocker's power, the Stone of the Earth, Tsukikage manipulates Tsukasa with the belief that he could stop the destruction of worlds by defeating the previous Riders, helping him in setting up the battle royal tournament, which doubles as a ritual to raise the Dai-Shocker Castle. After Tsukasa briefly resumes his role as the Great Leader of Dai-Shocker, Tsukikage takes advantage of Sayo's hatred towards her brother to organize a coup, swiftly overthrowing him to assume the throne for himself. Under his leadership, Dai-Shocker launches an ultimatum on the multiverse, ordering thousands of their own soldiers to perform kamikaze attacks and then releasing a legion of monsters to slaughter those who survived as part of their quest to assimilate all worlds into an interdimensional dictatorship.
• Kamen Rider x Kamen Rider OOO: Movie War Core: Seiichiro "Matsu" Matsui/Spider Dopant is the former partner of Sokichi Narumi, who became the first known Dopant with the Gaia Memory of the Spider. Obsessed with singer Melissa, Matsui threatened the lives of everyone at her concerts if she did not perform to his satisfaction and infected others with spider bombs that would detonate with them in the presence of their loved ones. Surrendering to his sadistic drives and jealous hatred of his partner, he went on a bombing spree to destroy Futo city, laughing while countless people lost their lives. Even after being defeated, he used a spider bomb to keep Sokichi from ever being near his daughter Akiko again.
• Kamen Rider W Returns: Eternal: Dr. Prospect/Eyes Dopant is a Foundation X scientist who kidnapped people from all over the world to make them into, in his own words, "lab rats" for his Quark Project by giving them Psychic Powers. When he arrives on the scene, every one of these people with psychic powers are utterly terrified of him, showing how horrifically he treated them. Even worse is his Heaven's Fall plan, which was so vile that Utopia Dopant considered it a brutal act. Prospect would blast the area with an electric pulse and that would kill anyone that had not lived up to his standards for the project, referring to this as "cleaning out the test pool". When Daido foils his plan, it is revealed that was merciful compared to what happens if they try to escape him. The eyes he implanted on them to watch them are used to kill them when they leave his compound. Dr. Prospect then laughs his head off at the fact he'd just slaughtered a village of innocent people while Katsumi is in shock over the massacre of the village he'd tried to save. His actions are so horrific that it drove Katsumi insane.
• Kamen Rider OOO Wonderful: The Shogun and the 21 Core Medals: The mad alchemist Gara, originally one of the four alchemists ordered by King OOO to create the Core Medals from him, is unleashed in the present day after having been sealed by the King for centuries. Gara immediately takes over King OOO's designs for his own, massacring the archaeological team that finds him and taking over the body of a nearby woman while attempting to kill her son in her body. Gara creates time distortions all throughout Tokyo, unleashing dinosaurs to rampage through the city and stranding Eiji and his friends in the Edo period, gauging the greed of the populace and trying to tempt Eiji into accepting a bargain that would result in the village of people he's saved vanishing from existence. Gara ultimately plans to obliterate the entire world, building up a new world of his own order atop the ashes to rule forever.
• Kamen Rider × Kamen Rider Fourze & OOO: Movie War Mega Max : Lem Kannagi/Super Galaxy King is a member of the insidious Foundation X and wishes to use the power of the Astro Switches and the Core Medals from the future to become an all-powerful being. He will do absolutely anything to accomplish this, while taking a sick glee in rubbing his advantage in the faces of his enemies whenever he gets the chance. He essentially kills Gentaro's girlfriend, Nadeshiko for the SOLU she's composed of, and then rubs that fact in Gentaro's face. He also had no problem killing anyone that gets in his way without an ounce of remorse, or creating clones of all the Greeed and Sonozaki Dopants for his own evil purposes of ruling all of humanity.
• Kamen Rider Wizard in Magic Land: Prime Minister Orma/Kamen Rider Sorcerer is Emperor Maya's deceitful advisor and secretly the Drake Phantom. Kidnapping Koyomi to perform a ritual that would create Magic Land, Orma assumes a high-ranking position and takes advantage of Maya's hatred for magic to use him as a Puppet King. Routinely kidnapping the citizens of Magic Land, Orma sacrifices them to construct the Thanatos Vessel, a machine capable of driving all mages living in Magic Land into despair, leaving only the bones of his victims as evidence of his crimes. When the Thanatos Vessel is activated, Orma mercilessly mocks Maya with the information that he condemned Magic Land, having manipulated him not because it was essential to his plan, but simply because he liked the idea.
• Kamen Rider × Kamen Rider Gaim & Wizard: The Fateful Sengoku Movie Battle:
  • Kamen Rider Wizard: The Promised Place: The Ogre Phantom, the first Big Bad, is a power-hungry, cannibalistic Phantom who hunts and devours other Phantoms to gain their abilities. Unable to be contained by Wiseman, Ogre targeted WizarDragon to be his next victim, intending on devouring him to become the strongest Phantom in existence. Stealing the Hope Ring from Haruto, Ogre uses it to resurrect a despair-filled Koyomi, asking if he will get her killed again or leave her alive to wreak havoc. Invading Haruto's Underworld with Legion's powers, Ogre attempted to consume WizarDragon, incapable of realizing that it was now Haruto's symbol of determination.
  • Kamen Rider Gaim: Sengoku Battle Royale!: Bujin Gaim/Kamen Rider Bujin Gaim, the second Big Bad, is the alternate counterpart of Kamen Rider Gaim in an Alternate Universe where warring tribes accompanied by Bujin Riders strive for supremacy. Beholden to no lord, unlike his fellow Bujin Riders, Gaim leads his armies and exterminates clan after clan in his path of conquest, tearing apart countries while capturing the souls of the Bujin Riders and massacring everyone else. With an army of enslaved Bujin Riders and the power of the "Miko of Fate" whom he seeks to sacrifice, Bujin Gaim desires nothing less than to rule the world.
• Kamen Rider Gaim: Gaiden: Kamen Rider Duke/Kamen Rider Knuckle: Kugai Kudo/Kamen Rider Saver is the former director of the Yggdrasill Corporation Laboratory before Ryoma Sengoku. After having his physical body destroyed during Ryoma's first experiment involving a Lockseed, Kudo became a supernatural entity who proceeded to form his own Apocalypse Cult, the Black Bodhi. Mass-producing the Zankuro Lockseeds, Kudo brainwashes innocent civilians with them and forces its users to commit suicide bombings, leaving the man behind Neo Baron to carry out his legacy by activating the Saver System, which would wipe out all of Zawame City except for the "strong". Returning in the Tie-In Novel, Kudo provides the The Mafiya and a rebel army from a South Asian country with equipment, including the Zankuro Lockseeds. Spreading a wave of crime in Zawame City by giving the Zankuro Lockseeds to a gang leader, Kudo manipulates more people into joining his cult as the only way to salvation and has the Saver System control the minds of countless people in the city, planning on assimilating all of humanity into Overlords.
• Kamen Rider Heisei Generations FINAL: Build & Ex-Aid with Legend Riders: Kaisei Mogami is a Mad Scientist with an Inferiority Superiority Complex. Believing himself to be smarter than his former partner, Takumi Katsuragi, Mogami began working for Juzaburo Namba and teamed up with his alternate self, a Foundation X researcher. Creating the Enigma, Mogami intended to use his machine to merge the two worlds and collide them with each other, leaving only him alive as an omnipotent being, the Bikaiser. Using innocent civilians as batteries by infecting them with Nebula Bugsters, Mogami revives the Horoscopes and the Greeed to distract the Riders, ordering Ankh to attack Eiji, fully knowing that he was his best friend, while mocking the Riders with the information that they could watch the destruction of their worlds.
• Kamen Rider Amazons: The Last Judgement: Einosuke Mido/Kamen Rider Amazon Neo Alpha is the militant anti-Amazon director of the Amazon Livestock Project and one of the worst examples of a Boomerang Bigot in the franchise. As a human-Amazon hybrid working for the pro-human leader of 4C, Mido keeps the original Alpha as his slave and routinely takes his cells to raise herbivore Amazon children, brainwashing them with the nihilistic philosophy that they are born to serve humans, converting an orphanage into his own Amazon Farm. When the orphans are ready, Mido sells them to rich humans and they are butchered to be made into exquisite food. After one of his orphans retaliates by killing an important politician who would greenlight his project, Mido is furious to see that such "cattle" could "dare defy noble humans" and rampages through the orphanage and outside, gunning down several orphans in his path while informing them that "cattle don't need dreams".
• Kamen Rider Heisei Generations FOREVER: Tid/Another Kuuga is a Time Jacker who attempts to conquer the world by completely eradicating the history of the Heisei Riders, taking the young child Shingo who exists as a singularity point in time–-thus keeping the Kamen Riders existent in the world–-and sealing him away forever to destroy their timelines and render them as nothing more than fiction in his world. Attempting to brainwash the heroes and trying to murder Shingo's own brother, Tid eventually raises a tower in the middle of a large city and has monsters wreak wanton havoc all throughout the city, eventually assuming his form as Another Ultimate Kuuga and vaporizing swathes of innocents himself. Tid attempts to annihilate everything that lives in the throes of his breakdown, declaring he alone "deserves to smile".
• Kamen Rider Build NEW WORLD: Kamen Rider Cross-Z: Killbus/Kamen Rider Killbus is the flamboyant king of the Blood Tribe and Evolto's abusive older brother who turned his own people into a faction of intergalactic exterminators to kill everything that exists in the universe, including himself, for fun. Years before the events of the show, Killbus destroyed his own home planet and ordered the rest of the Blood Tribe to begin their campaign of mass genocide to annihilate other civilizations across the universe. Searching for his brother to reclaim the Pandora Box for himself, Killbus massacres a news team and tries to kill him to finally achieve his destructive dream.
• Kamen Rider Zi-O: Over Quartzer: SOUGO Tokiwa/Kamen Rider Barlckxs is the leader of Quartzer. Orchestrating the events of Kamen Rider Zi-O, he, after Sougo unlocked Grand Zi-O's power, sent Kagen and Jogen to the Sengoku Era to eliminate Krim Steinbelt's ancestor and thus prevent the creation of the Drive Driver, which would in turn negate the Grand Zi-O Ridewatch. When Black Woz steals Ridewatches and delivers them to SOUGO, he reveals that he was the mastermind behind Sougo's rise and how he used Sougo as a "body double". Defeating Zi-O and imprisoning him SOUGO begins his ultimate plan: to use a portal to smash the World of Zi-O into the world from the first year of Heisei and erase the history of the Kamen Riders, so that he will rule it as King of Time; said plan, if successful, would destroy all life in the multiverse. When Black Woz betrays him, Tokiwa stabs him with his sword.

Kamen Rider Novels

• Kamen Rider Faiz (555) Seiden: Grotesque/Deformed Flowers: In this non-canon novel adaptation by Toshiki Inoue, Masato Kusaka/Kamen Rider Kaixa manages to be much more repugnant and heinous than he already was in the show. In the past, Kusaka was one of the "Ryusei Children", orphans raised to be able to successfully wear the drivers. Bullied by his peers, Kusaka had Mari to keep him company, but unbeknownst to her, Kusaka only saw her as a possession, rather than a real friend. When his classmates are attacked by an Orphnoch, Kusaka generalized the entire race as being monstrous abominations who deserve to be destroyed by him, even if there are good-hearted Orphnochs. Upon getting hold of the Kaixa Gear, Kusaka took the chance to try and kill all Orphnochs and keep Mari only to himself. Kusaka was responsible for the murder of Yuka, another bullying victim and a close friend to Kiba, driving him to hate the human race. After killing several innocent people, Kusaka rapes Mari, not caring if the assault had left her hopeless and depressed. Kiba is so disgusted by this that he personally rips off Kusaka's limbs as punishment for his crime. Later, Kusaka resurfaced once again to make Mari's life a living hell, but was ultimately stopped and killed by Takumi Inui. A calculating, antisocial bigot who saw others as mere objects for him to use in his genocidal quest, Kusaka served as a brutal example of how even the worst kinds of people can become Riders.
• Kamen Rider OOO prequel novel by Nobuhiro Mouri: The original Kamen Rider OOO and the Greater-Scope Villain of the TV series was an ancient king of a lost civilization who wanted power over anything else. He had three alchemists and Gara create five sentient creatures, the aforementioned Greeed, for the sole purpose of killing them off to reach his goal of becoming an immortal god. After the alchemists and Gara succeeded, he betrayed them and turned them into cell medals, with Gara still being conscious in this state. He then stole the core medals from the Greeed even though that would kill them over time. He used this power to take over a large portion of Europe and was well on the way to taking over the world; cloned himself to attack neighboring countries; burned down villages that opposed him; invaded enemy camps using subterfuge; and used earthquakes and tsunamis to wipe out the Spanish Armada. After Ankh betrays the other Greeed by working with him, he double-crosses Ankh and stabs him in the back for his Core Medals and causes all the Greeed to be sealed away just so he could have the medals for himself.
• Kamen Rider Kuuga novel by Naruhisa Arakawa: Go-Raio-Da, the Lion Gurongi is the most successful player of the Gegeru, possessing the highest number of intended victims: 1.6 million. Posing as a young amnesiac, Raio was adopted by an important figure in Japan and quickly became a beloved politician, using his connections to invent a drink called Lionel, tainting it with his own secretions, which he could telepathically control to damage the human brain. Disposing of his foster father as a way to increase the sales of Lionel across the country, Raio had over a thousand people killed in his "little sideshow", gleefully mocking an airplane pilot who had plunged into a building.
• Kamen Rider Ryuki novel, by Toshiki Inoue: Takeshi Asakura/Kamen Keiyakusha Ouja is even more depraved than his original counterpart. Killing his mother when he was still an infant, Asakura graduated into a Serial Killer by the age of six, killing two other children specifically on their birthdays and two counselors. Living in a homeless colony where he was idolized by the people, Asakura repeatedly stabbed the village's elder in the head and committed a killing spree targeting those who loved him, mutilating a man even after the latter had hugged him. While hiding, Asakura attacked a group of children with an ax and hung the bodies of five police officers from tree branches. Arrested for killing countless victims, two of which were Miho's parents, Asakura accepted the offer of becoming a Contractor merely because it gave him an opportunity to torment people without having to worry about consequences, going as far as to remove Raia's intestines. After barricading himself inside a convenience store, Asakura brutally murdered the staff members and customers, dismembering their bodies afterwards. Destroying lives simply because people smelled horrible to him, Asakura was a heartless savage who wished to fight for eternity.
• Kamen Rider Faiz: Seiden: Grotesque/Deformed Flowers, by Toshiki Inoue: Masato Kusaka/Kamen Rider Kaixa manages to be much more repugnant and heinous than he already was in the show. In the past, Kusaka was a lonely and bullied orphan who only had his friend Mari to keep him company, but unbeknownst to her, Kusaka only saw her as a possession, rather than a real friend. When his classmates are attacked by an Orphnoch, Kusaka generalized the entire race as being monstrous abominations who deserve to be destroyed by him, even if there are good-hearted Orphnochs. Upon getting hold of the Kaixa Gear, Kusaka took the chance to try and kill all Orphnochs and keep Mari only to himself. Kusaka was responsible for the murder of Yuka, another bullying victim and a close friend to Kiba, driving him to hate the human race. Not satisfied with his crimes, Kusaka rapes the underaged Mari, not caring if the assault had left her hopeless and depressed. Kiba is so disgusted by this that he personally rips off Kusaka's limbs as punishment for his crime. Later, Kusaka resurfaced once again to make Mari's life a living hell, but was ultimately stopped and killed by Takumi Inui. A calculating, antisocial bigot who saw others as mere objects for him to use in his genocidal quest, Kusaka served as a brutal example of how even the worst kinds of people can become Riders.

Kamen Rider Manga

• Kamen Rider BLACK manga: Kohtaro Minami/Kamen Rider Black himself is the Demon King in the Bad Future of 2018. Achieving the position of Gorgom's majesty by killing his rival stepbrother, Kohtaro started a war by launching nuclear bombs towards every continent, eradicating human civilization and forcing the few survivors to live in tribes. Kohtaro routinely orders his troops to attack any colony that they come across and kill everyone inside, allowing them to dismember corpses and slaughter babies. Recognizing his younger-self and desperately trying to preserve his own existence, Kohtaro argues to have done nothing wrong as he was "simply the ruler of this world". Proudly calling himself a "truly all-powerful Demon King", Kohtaro reveals that he has drained the energy of the planet just so he could "take this world to hell with me" in the event of an assassination.
• Kamen Rider ZO manga: Doras is the monstrous Evil Counterpart of the titular Kamen Rider, and far more evil and intelligent than he was in the film. Created by Dr. Mochizuki as Masaru Aso's superior successor, Doras trapped Mochizuki in a pile of biomass when he refused to complete his body and decided to go after his only son, Hiroshi, planning on using the boy as a hostage. After arriving at a junkyard, Doras assembles a body for himself and destroys everything in his path, leaving an entire block filled with corpses before converting Masaru's Love Interest into a grotesque monster who proceeded to kill even more people, forcing Masaru to end her life. Suspending Hiroshi with tentacles, Doras threatens to execute the boy in front of his father if he doesn't help him in ruling the universe as a god.
• Kamen Rider Kuuga manga: Akira Harada is a psychotic Serial Killer who, upon witnessing the first player of the Gegeru, Zu-Gumun-Ba, the Spider Gurongi, massacring humans on a railway, decided to worship Gumun as his goddess. A registered sex offender, Harada had tried killing himself for his goddess, and when he failed, Harada came up with the idea of "sharing his dream" with other people. Prior to having his identity revealed via DNA analysis, Harada had already murdered four women; by opening their chests, filling them with gunpowder, and burning them alive so they could become "human fireworks". When encountered by the detective investigating his murders, Kaoru Ichijo, Harada had killed another woman, and laughed at her death. Transported to an ambulance after attempting suicide, Harada slits the driver's throat and brags about being able to resume his serial killings. Harada is found by Gumun on the parking lot, and when he sees the remains of the creature's victims, he feels joy, seeing this as his goddess's work. A childish maniac with an obsession for fireworks, Harada was proof that the Gurongi are not the only beasts roaming Tokyo.