Who is your ultimate villain? I would lean towards movie villains, but if you prefer you can list book villains too. And tell us why, not just who.

Since I myself find this a difficult thing to narrow down, I propose the following sub-categories if you so choose to use them:

Best villain to love (in other words, you're actually rooting for him to win the day):

Best villain to hate (or that villain you simply despise because he's so twisted, but you nevertheless find him/her fascinating):

Best villain to love to hate (in other words, this baddie is evil, but you find perverse pleasure in his nefarious actions):

Other (anything you can think of, such as coolest fighter, best dressed, weirdest, least villainous, or anything else that makes the character enjoyable to you):

Myself? Hmmm...

Best villain to love: Grand Admiral Thrawn

Best villain to hate: Baron Vladimir Harkonnen (from the novel Dune, not either film version)

Best villain to love to hate: Darth Vader (OT version) or Khan Noonien Sing

Other: Not sure at the moment.

I may revise or update my list, but these are the first names that come to mind at the moment.