Scar. No question. I've noticed that often (I'm not sure if this applies just to Disney or in general) the best villains are the ones that try to come to power. Scar is my favorite because (number one) the laugh, you are not a true villain unless you have an evil laugh. The laugh is the reason that the others were on my favorite list as well. (number 2) He was willing to do anything to be king. I mean he killed his effing brother!!!! and smiled evily at it. (number III) Possibly the best reason (well not the best but just under the laugh reason) "Long live the king." He said it so evily to Mufasa. And it was said in an excrutiatingly ironic way but it also had a double meaning. The irony in the statement, and then the fact that Mufasa was going to die (and his knowing that Simba would be next) also said that Scar would then be king so 'Long live me.'
DC Comics: The Joker. And NO! The Joker was my favorite DC villain BEFORE Dark Kinght!!! Again, my favorite villain for the laugh. There was one point where I kind of accidentally sounded like him when I laughed although I never did the all out scream towards the end..... well I did but that's another story all together. ( I wanted to use a joker pic that looked insane but I also wanted to use the classic carton joker so ya)


Marvel:....don't know
Other: Eris from Sinbad Legend of the Seven Seas. Her laugh wasn't all that great but she still had the means for death on her mind, and her entire purpose was chaos which was just beautiful. The way she travelled, by way of...uh smoke(?) was pretty cool, I would love to be able to move like that. That would just about be the sickest thing in the world. 

(never can I write 'the' right the first time)