Imagine the scene: the hero has defeated the villain, defused the bomb and/or saved countless lives over the course of their 120-minute adventure. All that's left to do is applaud the protagonist for their sterling work and hope their happy ending with the lead romantic interest doesn't end up in a quickie divorce court...and then a plot twist derails the whole movie to reveal that the hero isn't even a hero at all. It's a tried and tested trope, and some would say an overused one; dumb slasher movies often have a 'surprise' villain who was one of the nerds from an earlier scene or a brash jock that's into snuff porn and incest (okay, maybe we saw that one coming a mile off), but the way to truly make a bait-and-switch twist like that hit home is to have the turncoat be a beloved central character sometimes even the protagonist themselves. Those are the moments that make an audience sit up and yell OH NO YOU DIDN'T at the screen and bestow the characters with legendary status. There are two major kinds of heroes-but-really villains as identified by that ever-flowing font of trivia TV Tropes: the Secretive Killer and the Amnesiac Killer. The former's true identity is kept a secret from the audience (and usually the rest of the cast) until it's revealed to another main character that their best friend/butler/dog was really the mastermind behind the art heist/president's murder/deadly space station, while the latter doesn't even know they're a villain until someone either lets them know or they stumbles upon their true identity by accident. Both can make for compelling watching and the ability to be able to watch a film for a second time in a completely new light. The following list contains ten of the best and most heartbreaking examples of good guys gone bad we could find...
