Splinter is a mutant rat and the adoptive father of the Turtles. He serves as their teacher and father, providing and protecting them with strength, guidance and devotion. He also has a wicked sense of humor, providing a quip or two at times for a good laugh.Splinter's history has varied within TMNT history.In the 1987 and 2012 cartoons, he was a Japanese-born ninja named Hamato Yoshi, who had a fierce rivalry with another ninja, Oroku Saki (who later became the Shredder). He eventually left to seek a peaceful life in America, and bought four pet turtles to keep him company; however they came in contact with a can of mutagen, which mutated them; Splinter having spent time with sewer rats, was mutated into a rat, while the turtles were mutated into human creatures since they spent time with humans.In the 1990s films and 2003 cartoon he was Hamato Yoshi's beloved pet rat. Yoshi was murdered and Splinter was made a homeless wanderer; he found his way into the sewers, where he and four baby turtles came in contact with mutagen, which mutated them all into humanoid characters.In the 2014 film, he and the Turtles were laboratory animals who were subject to tests with mutagen; when their laboratory was destroyed, they ended up in the sewers and as time passed they eventually acquired humanoid characteristics. He has no connection to Hamato Yoshi at all.