Who's your favorite villain and why?

Aaron the Moor from Titus Andronicus. Grotesquely, cartoonishly evil, but he uses it to serve very understandable motives. And his monologue is the best villain speech ever.

Medea from Greek myth. Ten times smarter and more powerful than everyone around her, but tragically in love with a schlubby doof that never appreciates her and probably thinks she's terrifying.

SPOILER from Danganronpa v3. A pathetic, lonely nerd desperately wanting to escape into her own fanfiction, even when she knows it dooms her. And then after she succeeds, it doesn't even make her happy.