Disney has some great villains... and some are really really dark. I guess I cant really say this is your favorite villain more as favorite antagonist because really, is Gaston that bad of a guy? Is he really a villain? SO what is your favorite Disney ANTAGONIST? Mine personally is Hades. I actually really love Hades. He's sarcastic beyond all "hell." Do you know how much he has to put up with in Hercules? I feel more bad for him then I do any other character. And James Woods makes for a really really good bad guy.
SCAR His personality is rather interesting to watch on screen, the voice goes with it so well, and he has one badass "theme" also because he dies in kingdom hearts
Barbossa to be different. He died in Kingdom Hearts. And he is just a creepy character and it is awesome.
Jafar. That final battle with him in "Aladdin" always sent chills down my spine as a kid. He also dies in Kingdom Hearts, though after that, they should've stopped bringing back Agrabah in the series (even though I thought Agrabah was handled better in Days than in CoM). And now this is starting to feel irrelevent to the main topic...
