Master Splinter (real name Hamato Yoshi) is a character from the 1987 series of Teenage Mutant Ninja Turtles.
He was voiced by Peter Renaday.
Yoshi was originally human and originally came from Japan. He was once the leader of a ninja clan called the Foot. He was once the teacher of Oroku Saki, who constantly challenged him in an effort to usurp his leadership. He would be banished from the clan when Saki framed him for attempted murder. Yoshi fled to the United States in poverty and lived in the sewers of New York City, befriending the rats that lived in them. He would eventually care for four baby turtles when they fell into the sewer and onto Yoshi.
Hamato Yoshi's human form.
The turtles would then come into contact with a strange goo, which turns out to be a mutagen that causes whoever that comes into contact with it mutates into whatever creature they most recently made contact with. The turtles became humanoid as they recently made contact with Yoshi, and Yoshi became an humanoid rat due to his recent contact with rats.
He would raise the turtles and teach them the art of ninjutsu to better defend themselves. The turtles gave Yoshi the nickname "Splinter", which he states was for "obvious reasons", due to his proficiency in breaking wooden boards. Splinter would name the turtles after his favorite Renaissance artists: Leonardo, Donatello, Raphael, and Michaelangelo.