Mandalore76 on 04 October 2018
Aside from the terrific ones already mentioned (Captain Cutler, Space Kook, Charlie the Funhouse Robot, etc..) there was the Witch Doctor (from "Scooby Doo, Where are you?"):
And, this one in particular spooked me when I saw the episode as a kid:
The Cat Creature from "The Scooby Doo Show" episode "Make a beeline away from that feline".
