Did I miss something, or has no one bothered to mention Keyser Soze (The Usual Suspects) yet?
Q…
more a brat than a bad guy… he did put the human race (and data) on trial.
The Kurgan? He is awsome! Clancy Brown can be the bad guy any day.
Mrs. Danvers in Rebecca
Has anybody mentioned Sands, played by Johnny Depp in the new movie Once Upon a Time in Mexico? The man does terrible things without hesitation, yet it’s hard to stay mad at him.
Somebody beat me to Iago, but Shakespeare’s a pretty deep well when it comes to villains, so I’ll pull out Aaron, the mischievous Moor from Titus Andronicus. He’s very frank about his own character, and cheerfully admits,
Tut, I have done a thousand dreadful things
As willingly as one would kill a fly;
And nothing grieves me heartily indeed,
But that I cannot do ten thousand more.
As for his idea of fun, he states,
Oft have I digg’d up dead men from their graves,
And set them upright on their dear friends’ doors,
Even when their sorrows almost was forgot;
And on their skins, as on the bark of trees,
Have with my knife carved in Roman letters,
“Let not your sorrow die, though I am dead.”
Man, that’s hardcore.
I honestly can not believe you people 
How can you talk about villains and not mention Gary Oldman in 5th Element and Leon. Psycotic, moraleless and 100% pure grade A evil.
Alan Rickman in Diehard and Robinhood comes as a close second (the spoon qoute is permanently engraved in my memory)
As far as books go how about Shrike and Radmanta Nemez from the Hyperion series, very colorfull pair considering both have the ability to pause reverse and twist time and very frequently tear people to shreds in slow and painful ways.
well, my favorite has already been mentioned. Alex in a clockwork orange. but I can’t believe no one has mentioned Deacon Frost from Blade. Stephan Dorff pulled that roll off. also, Val Kilmer as Doc Holliday isn’t exactly a paragon of virtue, but he’s a damn cool character.