No ranking:
El Indio- Murdering a child and mother immediately after breaking out of jail pretty much sums up this guys character. And the fact that he still carries around the locket implies that his rape of the Major's sister and killing of her husband is a fond memory. Then he toys with the lives of his own men and sets them and the hunters against each other at least partially for amusement. He's such an irredeemable villain that the Man With No Name takes notice and seeks to ensure his death in a righteous manner, putting aside his mercenary ambitions to allow the Major some revenge.
Queen Jadis, the White Witch- She's probably the most downright despicable villain who most kids will encounter early into their reading life, she was played perfectly by Tilda. Swindon in the movies, and she freaking murders Aslan while personally seeking to destroy any hope and pride he has. But what really seals it for me is her past in the world of giants, where she is portrayed rather frighteningly similar to regular human fanatic, and you realize she really doesn't change by the time we see her again.
Emperor Palaptine- Ian Mcdiarmid gave us a bad guy we knew was worse than Vader or Tarkin within seconds of his introduction and remains the most consistently watchable part of the entire saga thus far. And the story and action embrace the transparency of his Clone Wars scheme and make you believe "This...could actually work." And his manipulative nature crawls at you from the screen; after the opera house scene, you know Anakin's doomed because damn, that was a great story. And you love to hate him so much that Mcdiarmid can flip to devouring the entire scenery and you won't care. The man has "POWER! UNLIMITED POWER!!!"
Harry Lime- Orson Welles smacks you upside the face with his acting wang. Ten minutes of screen time and we have a love-able but desperate petty crook turned major racketeer who puts selfishness and greed into six clear, human sentences. "Victims? Don't be melodramatic. Look down there. Tell me. Would you really feel any pity if one of those dots stopped moving forever? If I offered you twenty thousand pounds for every dot that stopped, would you really, old man, tell me to keep my money, or would you calculate how many dots you could afford to spare?"
The Joker- He is now the archetypal Evil Clown, and in spite of the varying censorship rules across the multiple media he has appeared in, he remains the most injurious villain to be opposed by a hero. Crippled Barbara Gordon, killed Jason Todd, brainwashed Tim Drake, kills Lois Lane and Baby Kent, killed Sara Essen Gordon, killed Rachael Dawes, created Two -Face. If a writer for superheroes needs someone to maim the hero's loved ones, he's the man to call. And though he does lose every single time, he's the only villain for whom winning or losing doesn't matter. Kill him, imprison him, break his bones and bury him. He's coming back, and you will scream.