Leatherhead is an oft-ally of the Turtles that first appeared in Tales of the Teenage Mutant Ninja Turtles #6. Originally, Leatherhead was nothing more than an infant alligator that had escaped a robbery at a pet store, and found its way into the sewers. While in the sewers. Leatherhead was found by a pair of TCRI Utroms who decided to bring the creature to their headquarters. During his stay with the Utroms, Leatherhead was exposed to Mutagen, which caused him to mutate into a humanoid and intelligent being.