Almost every villain is my favourite villain. Although they (almost) always loose, the villians are just the coolest
I guess my latest favs from the oldest to my most recent fav were:
Ganondorf
Dr. Ivo Robotnik
Darth Vader
Invader ZIM (hmm, isn't Dib the "villain" in this show?
)
and most recently:
Lord Saddler from Resident Evil 4, he's kinda cool