I have to say Maleficent mainly because all other Disney villain is after something the requires them to be evil. Maleficent on the other is just evil just for the sake of being evil. She doesn't need a kingdom, trident, throne, shiny objects, for a mirror to say she's pretty, and any other situation that would require and plan that karma would frown upon. She's simply evil just to ruin people's days in a elaborate fashion, and she can turn into a dragon which helps things along.