Azula Ozai from Last Airbender (the baddest cartoon villain bish to ever do it)
Lex Luthor
Poison Ivy
Megatron
Aku from Samurai Jack
Catwoman (even though she's more of an anti-hero than a villain)
Live Action Villains:
Francis and Claire from House of Cards
Alexis Carrington from Dynasty
J.R. Ewing from Dallas
Stringer Bell and Prop Joe from the Wire
Al Swearengen from Deadwood
You know, I'm really having a hard time coming up with live action villains that I genuinely love. I need to watch more live action dramas or something . . .