Evil Villian...hmm..in my opinion that would be Dark "Yami" Marik from Yu-Gi-Oh! most definitely he truly is a dark character,he sent so many to the "Shadow Realm" as they called it in the dub,well he is rather smart and sly,especially in dueling Kujaku Mai-chan..he may be scary,but certainly is the best villain I can think of,but it is twice as scary and psychotic in the Japanese episodes!x) tee hee.
Apos is pretty evil, but he's और of a sadistic-torture evil rather than mass murderer या a mess-with-your-mind evil. He doesn't kill people directly except for maybe twice. I say "he" but Apos is neither fully man nor fully woman but they portray Apos as a man so.
I found a pretty sick picture but आप couldn't see Apos's head so I put another full body one beside it.