Splinter, often referred to as Master Splinter by his students, is a fictional character from the Teenage Mutant Ninja Turtles comics and all related media. A mutant rat, he is the martial arts and ninjutsu instructor of the Turtles, as well as their adoptive father. In most incarnations, Splinter is a mutated or reincarnated martial artist Hamato Yoshi; in others, including his original incarnation, he was Yoshi's pet rat.