danithew

Demons from hell should probably be added to the list (a la Doom - the game, not the movie).

Also, there's that special category of human mutants who have been debased and deformed by falling into radioactive slag.

There are some special characteristics that, when combined with evil, make for a great enemy.

Insanity ... (ex: the Joker, in Batman or Mr. Glass in Unbreakable). It can't simply be a matter of mental illness ... evil has to be added to the mix.

Intelligence ... (Hannibal Lecter).

It certainly is interesting to consider the role that deformity plays in making fictional evil characters more interesting. Often that deformity has to be covered with some kind of mask. Darth Vader, Dr. Doom, etc. and etc.