18. Mystique

Not every great villain has to be a world-conquering, war-mongering, super-powered bad ass. Some of them are simply great at manipulating events to their liking, bending the world to their desire and getting away with it. Mystique is one of those villains, and is absolutely one of the greatest female villains ever created.

Raven Darkholme's history is a bit convoluted, particularly as she relates to the complex X-Men history, but that's not necessarily what makes her important. The key points would be these - she is the mother of Sabretooth's son, the mother of Nightcrawler and a foster mom for Rogue. Her history with these various characters has given her a prominent seat in the future of the mutant race, and she even played a critical role (despite being revealed as a traitor) in the 2006 storyline Messiah Complex, which kicked off a major new era in the history of the X-Men franchise.

Due to her age (which is estimated at over a century), Raven has played a role on many teams, involving herself in many causes including the X-Men, Brotherhood of Evil Mutants, X-Factor, Marauders and more. Most recently she was involved in clashes with Wolverine (who sought revenge for her betrayal in Messiah Complex) and Iceman, where she apparently died. Given the number of times she's allegedly been killed, it's hard to imagine this espionage master will remain missing in action for long.

In essence, over the years X-fans have been treated to a kick ass femme fatale who has found herself at several key turning points in the history of the mutant race. Oh, and you have to love her design, both in film and print. 'Nuff Said.