How about Roy Batty from Blade Runner? Is he considered as evil character? But, by end of the movie, he is not so evil or atleast his evilness is understandable. Or, is Deckard the evil character? But, he is depicted as a good person protecting the Earth. That's why I think either one of them can be candidates for the greatest villian character b/c the "greatest"/"scariest" evil is not the one with sharp tooth or coldblood but the one which is most pesuasive, i.e., which could be anyone of us.