You all know this info, I'm sure, but I'm just layin' it out 'cos it's popped up in my mind periodically for like a decade now:
First off, there are five different games with the exact same title: Devil's Castle Dracula (since they all pertain to Simon Belmont, so they're all remakes of the first game in a sense, story-wise);
Castlevania II: Simon's Quest is titled Dracula II: The Seal of the Curse (actually, I prefer the translation "The Accursed Seal", whether it's more accurate or not);
Castlevania III: Dracula's Curse is titled The Legend of the Devil's Castle ("Dracula's Curse" would have been a more fitting subtitle for Castlevania II, by the way);
Castlevania: The Adventure and Castlevania II: Belmont's Revenge (Game Boy games, hence why there are two games known in English as Castlevania II) are titled The Legend of Dracula and The Legend of Dracula II, respectively;
Castlevania: Bloodlines is titled Vampire Killer (which is the name of the English release of the MSX2 version of Devil's Castle Dracula);
Castlevania: Circle of the Moon is titled Akumajō Dracula: Circle of the Moon—yes, with an English subtitle (all the previous games' titles are in Japanese, of course, aside from Vampire Killer and the name Dracula), and also the only time both the English and Japanese releases share the same subtitle (Symphony of the Night vs. Nocturne in the Moonlight, Harmony of Dissonance vs. Concerto of the Midnight Sun, etc.);
and at one point they started calling the games Castlevania in Japan before switching back to Devil's Castle Dracula (Akumajō Dracula). Yeah... Weird "system" of naming.
Devil's Castle Dracula, Dracula II (dropping the "Devil's Castle"), The Legend of the Devil's Castle (no "Dracula"), The Legend of Dracula (no "Devil's Castle"; these games and Akumajō Densetsu effectively swapped which parts of the original game's title they use in conjunction with "Densetsu"), Castle-freakin'-vania at one point (didn't go over well over there, I hear)... What strangeness.
And really, "Castlevania" is such a silly and cheesetastic title—I absolutely love it.