There's a reason why movie villains so often steal the show.
Whether it's Loki, Darth Vader, Magneto or The Joker, the bad guys don't have to play by the same strict rulebook our heroes usually do, meaning they can be funny, devious, likeable and scary all at the same time, a concoction that usually proves engaging and interesting.
As such, a movie's villain is always one of the most talked-about elements leading up to release, but this hype can be dangerous, especially when it creates expectations which aren't always met. What if that villain barely gets any screen time? What if they just aren't intimidating? Or, what if it turns out an even bigger enemy had been lurking behind the scenes the entire time?
Discovering that who you thought was the lead bad guy is actually second-in-command, a henchman or a pawn in a higher power's game can be quite jarring, and it can either make you appreciate the character even more, or hate what they've become.
Now, these ten villains aren't necessarily poorly portrayed or ineffective, it's just that their position as the main antagonist wasn't as secure as we were all lead to believe.