When a villain walks on screen it's pretty obvious. More often than not they'll be decked in all black, possibly with a cape, sporting a long and thin moustache and speaking in a perfectly annunciated British accent.
OK, things aren't that un-nuanced (although the accent trope is still around), but generally a villain is a pretty obvious character. At least most of the time anyway. A film may try and hide who its true villain is for a big, third-act reveal; maybe the bad guy is actually a close friend or mentor of the hero, or a background character whose secretly been behind whatever scheme's afoot the whole time. And when it's done correctly, it really works, shocking you into paying full attention as the climax looms into view
That, of course, is assuming that the twist wasn't actually painfully obvious. Too often not enough is done to hide these baddies true intentions. How many times has a character been so goody goody and irrelevant to the story that the only way for them to be worth inclusion in the story at all is to be the criminal mastermind?
Be it bad screenwriting or directors underestimating fans and their theories, these ten examples of villain twists we totally figured out before the reveal will show it's a bizarrely prevalent plot device.