I know it's redundant, but, Orochimaru.
I mean, c'mon, the first thing we know about the guy is that he rips off people's faces and gives little emo-kids hickeys.
But the part that REAAAALLLY creeped me off as a kid, was when he ripped his face while fighting against third hokage with zombie hokages, and there was a girl face underneat it, and then he/she began laughing really creepy and it was really weird....yeah. Anime michael jackson is the worst.