Teenage Mutant Ninja Turtles
Splinter's origin differs between versions. In some versions (Mirage, 2003, movies), he was originally a pet rat of Hamato Yoshi, ending up mutated. In other versions (1987 carton, Archie and the 2012 cartoon), he was originally a man, Hamato Yoshi, who ended up accidentally touching the ooze, and turned into a humanoid rat.