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File:Batknockoutgas 275 2609.jpg

"Holy Too-Sleepy-for-Puns, Batman!"

In fiction, one of the easiest ways to incapacitate an opponent or group of opponents is to get them in a closed room and pump in Knockout Gas. Knockout Gas is an area-effect form of Instant Sedation: as soon as the victims breathe it, they cough weakly a few times and then slump to the floor unconscious.

Usually delivered as a visible fog, and often brightly colored as well, but invisible gas is also common, particularly in budget-conscious productions. Knockout Gas can be delivered through special vents just for that purpose, or it can be pumped in through the regular ventilation system. As with other forms of Instant Sedation, dosage doesn't seem to matter. The effects last just long enough for maximum tension or drama. Recovery tends to be just as fast as the onset, and the victims rarely suffer any lasting effects beyond, perhaps, a mild headache.

Frequently employed by villains, but also a convenient weapon for heroes due to its non-lethal nature.

Subtrope of Instant Sedation. Sister Trope to Deadly Gas (and in Real Life, though almost never in fiction, the line between the two can be a very fine one.) Sister Trope to Tranquillizer Dart.

Examples of Knockout Gas include:

Anime & Manga

Comic Books

  • One of the most consistent ways of defeating The Hulk, at least on those occasions when he doesn't remember that he can hold his breath for hours. As the Hulk isn't all that bright, this is not infrequent.
  • Hawkeye uses trick arrows, one of which, is a knock-out gas arrow.
  • Batman has used knockout gas from various sources: bombs, canisters, guns, etc.
  • As with the movie and TV versions, the comic versions of The Green Hornet have also used knock out gas.
  • Enemies of Spider-Man have used it from time to time. Mysterio, Kraven, the Chameleon, the Hobgoblins, and Green Goblins are all culprits.
  • DC Comics' golden age hero Sandman used a knockout gas gun. Later versions of the character also used knock out gas.
  • In Amazing Spider-Man #661, Veil turns into isoflurane, an anesthetic gas, to keep two muggers down. True to the usual depiction, despite the gas generally being colorless, it appears as a thick fog.
  • In Jet Dream, Jet uses "Kayo Powder" in a makeup compact for this effect.
  • In Tintin in America, the Gangsters Syndicate of Chicago uses knockout gas on Tintin after dropping him through a Trap Door and before dumping him into Lake Michigan. Fortunately for Tintin, they used the wrong kind of gas.

Films — Animation

  • The short film Interstella 5555 that goes with the Daft Punk album Discovery starts off with an entire stadium full of concert-goers subdued by black suited mooks with devices that shoot pink gas. The entire stadium goes down in seconds. The one person who escapes is taken down with a specialized crossbow bolt whose head bursts into a similar cloud of pink smoke.
  • Megamind's Minion possesses a Knockout Aerosol can, which he mostly uses on Roxanne in her endless kidnappings. Halfway through the film he runs out of it and resorts to Forget-Me-Stick.

Films — Live-Action

  • Played with in the 1967 comedy Thoroughly Modern Millie where the antagonist is pumping a white sleeping gas into the room of someone she plans to kidnap and sell into slavery, the problem is that she is in the room with the gas. As the gas gets thicker in the room she starts to yawn, slows down, and finally just falls over onto the bed; the gas has dissipated by the time she is found, still asleep. It is then later played straight with darts that work instantly.
  • In The Film of the Series of The Avengers 1998 Father knocks Mrs. Peel out instantly with gas from an aerosol can.
  • In the 1966 Batman movie, Batman and the Penguin each use a gas that causes instant unconsciousness (called Bat-Gas and Penguin Gas, respectively).
  • Artemus Gordon's sleeping gas billiard balls in Wild Wild West. The logic of having sleeping gas disguised as a billiard ball is Lampshaded by Jim.

 West: Well I don't know about you, but I'm certainly gonna sleep better, assuming Loveless barges in here and wants to play a game of pool.

  • Britt's iconic Gas Gun in the 2011 The Green Hornet film. It instantly puts anyone to sleep for about an hour, though this was only after Kato experimented with and perfected it. The first mixture put Britt out for eleven days.

 Britt: I was out for eleven days?! I wasn't asleep, that was a coma, you dick!


 Ringo: It must be their tea break.

  • Animal Crackers ends with Harpo spraying everyone with knockout gas, including himself.
  • Diamonds Are Forever. While James Bond is in Willard Whyte's elevator, Blofeld renders him unconscious with knockout gas.
  • Even the great El Santo proves vulnerable to a knockout gas grenade thrown by a hunchback in Santo Y Blue Demon Contra Dracula Y El Hombre Lobo.
  • In the 2015 action movie, Mission: Impossible — Rogue Nation, Ethan Hunt is rendered unconscious by gas in the first act, only to turn the tables on the villain and use the same knockout gas in the climax of the film.


  • Lone Wolf features knockout gas in Castle Death, filling some trapped rooms or delivered by an ugly dwarf blowing it in your face through a brass tube.


  • Doc Savage used anesthetic gas grenades. Somewhat justified in that Doc was supposed to have specifically invented these.
    • In Fear Cay, one of the Doc Savage novels, the bad guys try to capture Doc with Knockout Gas dispensed from a rigged wallet left on the sidewalk where he would find it. It doesn't work, because of his superior ability to smell (he somehow smelled it before he breathed it) and (as with The Hulk) his ability to hold his breath for much longer than normal. In this case it was not visible.
  • The Alistair MacLean novel The Golden Gate has aerosol gas that cause instant unconsciousness.
  • Subverted in the opening scene of A Piece of Resistance by Clive Egleton. La Résistance use a knockout gas to remove an innocent bystander, who then dies of a heart attack.
  • Fighting Slave of Gor: Jason Marshall and his date Beverly are taken out by knockout gas in the backseat of a specially-prepared taxi. They were only after her, but he forced his way into the cab when she was trying to end the date.
  • In Harry Harrison's The Stainless Steel Rat series, both local law enforcement and Slippery Jim use Knock-out Gas with great abandon, although slightly more realistically than is usual in fiction. Jim makes sure to use nasal filters or a mask to avoid breathing it in himself, it's usually invisible rather than brightly coloured, and there are numerous different types, with different effects, speed of action, duration and after-effects.
  • Larry Niven and Jerry Pournelle's Oath of Fealty. The Todos Santos arcology uses knockout gas as part of its internal security system.
  • In Little Green Men, the "aliens" use a gas named sevoflurane to anesthetize their abductees, usually with added ammonia and cinnamon scent.

Live-Action TV

  • The Green Hornet has as one as his main weapons, the "Hornet gun", spraying "Hornet gas" that would knock out mooks with one sniff. This is a carryover from the original radio series and 1940s film serials.
  • The Prisoner. The sleeping gas used on Number 6 in his apartment in the first episode (and each episode's opening title).
  • A constantly-recurring staple of both villains and heroes on Batman, most often in the form of colorful Knockout Gas.
    • "The Bookworm Turns". The sleeping gas released by the Bookworm's booby-trapped book renders Robin unconscious in seconds.
    • "While Gotham City Burns". The Bookworm uses a package booby-trapped with sleep gas to render Alfred and Aunt Harriet unconscious so he can steal a book from the Wayne manor library.
  • Simon and Simon episode "Under the Knife" has A.J. gassed in a hospital room and in danger of unnecessary surgery when the brothers get too close to the truth in a malpractice scam.
  • Star Trek the Original Series episode "Space Seed". After Khan takes over the Enterprise, Kirk orders that all decks be flooded with Neural Gas, which would render everyone aboard unconscious. That attempt fails, but later the attempt succeeds.
  • In Wonder Woman season 1 episode "Judgment from Outer Space (Part 1)": she's taken down by knockout gas.
  • The Wild Wild West
    • In the episode "The Night of the Sudden Death", invisible gas pumped in from a gaslight lamp with an unspecified additive is used to fill a very large U.S. Mint set and knock out several people within seconds.
    • In another episode, Gordon uses Knockout Gas himself, but he's still dissatisfied with it because it's too visible.
  • In the "Biology 101" episode of Community, a variant of Knockout Gas intended for monkeys ("Chimpan-Zzz" brand) is pumped into the Greendale air vents. It turns out to work on humans too, with the additional side effects of causing hallucinations and references to 2001: A Space Odyssey.
  • In the Stargate Atlantis episode "Inquisition", Atlantis' first team is taken out by Knockout Gas in a cell, before being moved to another planet through the Stargate so the rest of the expedition can't find them.

Tabletop Games

  • Shadowrun. The various Neurostun gasses are often used to take out shadowrunners without killing them.
  • Dungeons and Dragons. At the end of module A3 Assault on the Aerie of the Slave Lords, a green gas (the "Smoke of the Little Death") is used to knock out the PCs so they can start the next module as the Slave Lords' prisoners.

Video Games

  • Thief has Gas Arrows: shooting a mook will knock him out even if he's fully aware of your presence (and thus would only get annoyed by the Blackjack). Shooting the ground has an area effect, knocking out everyone within a meter or so.
  • Deus Ex Human Revolution has Gas Grenades as one of the weapons in the pacifist player's arsenal. It's a generally useful tool for knocking out multiple enemies where tranqs, stun guns, and takedowns are just inappropriate, and everything else is overly lethal.
  • In the Apple II-era game Infiltrator and Infiltrator II, you use a canister of knock-out gas to deal with enemy Mooks (and I don't mean hitting them with the can). Works instantaneously every time.
  • The RuneScape quest "The Great Brain Robbery" has a section where Harmony Island is covered in knockout gas. You have to wear a scuba-diving helmet or you'll be knocked unconscious.
  • In Mega Man Battle Network 5, at the very beginning of the game, Lan, Dex, Mayl, Yai, and Yuuchiro are knocked out with bright pink sleeping gas, Yuuchiro is kidnapped, and everyone's navis except Megaman are stolen.

Western Animation

  • Jonny Quest TOS episode "The Quetong Missile Mystery". Sleep gas knocks out General Fong in a couple of seconds.
  • Family Guy Peter gave his rival a statue of himself that sprayed "Crazy Purple Knockout Gas!"
  • She-Ra: Princess of Power once features a scene where villain Hordak sprays one of the heroes with some sleep gas from his Swiss Army Hand. The hero gets off an exclamation and keels over. Hordak then comments that he's going to have to have a word with his scientists; the victim shouldn't have had time to say anything before succumbing.
  • Space Ghost episode "The Looters". Brak uses a sleep gas missile on a ship.
  • In one of the Gorillaz short animated idents, 2D is knocked out cold by just a whiff of gas.
  • Darkwing Duck uses a gun that could fire knock out gas (among other things). Due to the character being a little clumsy, he knocks himself out once or twice.
  • In Wakfu season 2, the Justice Knight captures fugitives with his Justice Train by trapping them inside the wagon, which then fills with a golden Knockout Gas. The effects are shown to be immediate even with the heroes.
  • Subverted in Archer, when Cyril thinks he's delivering a dose:

 Cyril: (procuring a briefcase I got the ten million in bearer bonds.

Spelvin: Unbelievable!

Cyril: Well, I...

Spelvin: No, I mean literally. I don't believe you. I suppose this is full of knockout gas or something... (opens briefcase to reveal a single cupcake)

Cyril: Apparently not.

Archer: (kicking in the door) Exactly! Because I don't know if that's even a real thing!