Cash Cow Franchise: Castlevania is one of the guiltiest in Konami for this; some Konami fans are complaining about the other titles cast aside, such as Contra.
Somacula, for the evil Soma in the bad ending of either Sorrow game.
"Whip Guy" and "Spear Dude" for the protagonists of Bloodlines.
For Simon's walk in Haunted Castle, "Wedgie Walk" or "Gotta Pee Now Step" apply.
Eeguh - Koji "IGA" Igarashi, the current producer of the series.
Japan refers to Chronicles Simon as either Red Simon (akai Shimon) or... Homon.
Castlevania (Nintendo 64) - The first Nintendo 64 game, properly named Castlevania, starring Reinhardt and Carrie.
The Belmont Walk; the Pimp Walk - A peculiar stride that all of the members of the vampire hunter clan Belmont use. This most likely originated from the four frames of animation use for Simon's walk from the original game, but other 2D Belmonts used it too, leading to the nickname.
Castlevanians of Ottawa-region like to call it "CastlevaNote".
On that note, let's see which other characters we can rename: Near Lecarde, Soicula Yagami, Misa Renard, Caryomi Takada, Mello Danasty...
The Samuel L. Jackson Attack - Shanoa's Nitesco + Weapon Glyph union from Order of Ecclesia that resembles a giant purple lightsaber, just like Master Windu's weapon of choice in Star Wars.
Holy Snorkel - The Holy Symbol relic from Symphony of the Night, which allows Alucard to survive underwater and happens to resemble a gold snorkle.
Fleaman - Originally called Hunchbacks, people started calling them Fleamen because of their erratic jumping, and the name kinda stuck, to the point that it's the official name in-game for them.
IGAvanias - For all the Castlevania games produced by Koji Igarashi, almost all of which were "Metroivanias".
Classicvanias - For all the classic stage-based Castlevania games prior to Symphony of the Night.
Metroidvania - For the post-Symphony of the Night installments in the series for their sprawling world map and wide open exploration. It has also become a nickname for an entire sub-genre of 2D action games offering similar mechanics (for better or worse)
3Dvanias - For all the 3D-based games in the series.
It would seem that Patrick Seitz is the go-to guy to portray Drac. Seitz has portrayed Dracula in The Dracula X Chronicles, Order of Ecclesia, and Judgment.
Tom Wyner (Devimon, M. Bison) voices Death in Lament of Innocence and Curse of Darkness, while Travis Willingham takes over in The Dracula X Chronicles and Judgment.
Vampire Killer on the MSX2. It doesn't help that the MSX is absolutely nonexistent in North America, making VK even more obscure.
Rondo of Blood was like this until just recently; ditto the Saturn version of Symphony of the Night.
Remade for the Export: Akumajou Dracula for the X68000 was introduced to gamers outside of Japan for the first time as Castlevania Chronicles. Similarly, Castlevania: Rondo of Blood made its first (functional, playable) trip outside of Japan as Castlevania: The Dracula X Chronicles. We don't talk about the SNES Dracula X.
What Could Have Been: Older Maria Renard was meant to be playable in SotN, but was scrapped due to time constraints (voice files can still be found on the disk). Nocturne in the Moonlight, the Updated Rerelease for the Sega Saturn, among other things, made Maria playable.
They Changed It, Now It Sucks: Some were not pleased that the Maria in the PSP release of Symphony of the Night was not like the Saturn version of her in combat.