It happens all the time on television: a character who originally started out one way suddenly finds themselves battling with a brand new persona, until - wham! - they're just a shell of their former selves. It's happening right now in The Office with the Andy Bernard character, who has changed his personality so drastically over the last few seasons of the show that he's just not Andy anymore, and because that's the only way the writers can deal with a series that apparently wants to go on forever. It happens less in the movies, but it does occur from time to time, and usually in sequels. Have you ever noticed that a character in one movie has changed their entire personality in a sequel? I don't mean that in the "arc" sense, like when that parrot Iago becomes a good guy in Aladdin:Return of Jafar (didn't know that, huh?), because there's an actual reason for it to happen and we understand why. But what happens when a movie character just shifts personalities completely, as if the old version of them never existed at all? Take the characters I've assembled for this list, all of whom suffer from strange, inconsistent, unexplained brain shifts in a whole bunch of movies...