31 Favorite Monsters: Mutagen Man
My single favorite mutant from the 1990's "Teenage Mutant Ninja Turtles" toy line and cartoon show, Mutagen man is surely one of the most grotesque and inventive designs for any children's action figure, consisting only of entrails in a glass tank with rotten, cybernetic limbs. He even had garbage inside, too! As I talk about here in greater depth, he's also one of the franchise's darker characters, working for the evil Shredder only because his body will fall apart without a steady supply of Mutagen Ooze.
Mutagen Man's design for the cartoon was a little toned down - I particularly miss the eyeballs being on stalks, like in the figure - but at least the basics were all there. He's restored to human form in the end, but with a pretty cute twist. Track down the episode, or at least read my above link!