'Ursula', who in Hans Christian Andersen's story orchestrates the destruction of all of the Mermaids, effectively destroying the bloodline of the royal mer-family.
Cinderella's stepmother, who in the original story forces her daughters to mutilate themselves in order to fit the shoe; also, Cinderella herself, who gets her pet doves to attack her stepsisters and rip out their eyes.
Hercules. As shown by Pak, he is a known warmonger, criminal, drunk, etc.; only, Pak is able to make us empathise with him and his cause. Even the above example demonstrates that he is capable of change.
Claude Frollo...actually, think they made him slightly worse than the original. Certainly, much creepier.