Use this for reference:
http://en.wikipedia.org/wiki/Walt_Disney_Animated_Classics
Och, can't really decide....
Frolo's one of the villains who really scared the poop out of me. Now, the movie ain't really as good as the horror of the original story, but damn, did they stuff a lot of dark beans into him! Cruella de Vil also scared me a lot, though when I first watched 101 Dalmatians I was too fixated on the puppies to really be scared of her.
But boy, that redheaded woman from The Rescuers (what's her name again? I keep forgetting), now she REALLY scared me. Frolo lived in the Middle Ages, and his struggles between the flesh and his creed I can actually relate to in a fairly sympathetic way; Cruella, meanwhile, only really hates on dogs. But that woman, Madame Medusa's the name, she's pretty damned scary; I mean, gods, she exploited child labor, and in a time period that I could really directly relate to! For a kid who was rather self-conscious with those sorts of things, she was the worst....
Hey, still not my favorite, though. She might've been the worst, but she wasn't really cool being the worst. Now, Ratigan from The Great Mouse Detective, that guy, he's the, err, mechanical bomb! Or maybe the rat....I mean, a real, non-magical supervillain in a Disney film? And one modeled after Sherlock Holmes's Moriarty? WHO CAN SING?
But no. My favorite would have to be Scar. Now that I think about it, killing a boy's dad is probably worse than abducting a little girl - and killing him in front of the boy's eyes! Boy, that guy's real, real evil. But hey - the lion's got quite a voice! - and, extending the context a wee bit, The Lion King is really my favorite Disney film of all time; it was, and is, for me, the Star Wars of animated films (and, in essence, its theme does follow the same, mythological thread). So, there you have it, my vote.
A little note: Gaston, I really enjoy as a villain, if only because he reminds me so much of all the unreasonable hatred in society, so that in the end, seeing him Disney-die, and seeing Belle get her happy-ever-after, feels much more, er, cathartic, I guess, than it should be. I don't really like him, however, so I can't be bothered to vote for him.
Further note: I disagree with the Red Queen being in that poll, if only because she was too loony to be an actual villain. That is, she's not really villainous per se, just, er, crazy-as-balls (and besides, of all the villains in the Disney pantheon, she's probably the least real, especially because, as established in the film, she isn't really real at all - although aside from that, she doesn't really have any motivation in the story, whether natural urge or otherwise, to be a "villain"; she hindered the protagonist, yes, but in the utter nonsense of her character she proved to be more like an accident than an actual antagonist). And if Clayton and the Poacher from The Rescuers Down Under are there, I demand to see Man in that list too! The hunters in Bambi were probably the best (in terms of narrative) part of the film!