Mr. Nasty is the eponymous main character in the episode "Angry Nasty People" of Courage the Cowardly Dog. He is the epitome of all of Eustace Bagge's nastiness. He starred in The Angry Nasty People show. He left the show when Benton Tarantella found a new star, Courage. Mr. Nasty went on to create his own talk-show with Eustace, who he swindled out of 95% of the profits.
Mr. Nasty looks identical to Eustace except that he wears black-lens glasses and emits a dark blue glow.