Hamato Splinter (Mirage)

Hamato Splinter is the teacher/father of the turtles and has taught them all they know.

Background
In the original comics, Splinter was the pet rat of a ninja named Hamato Yoshi (Mirage) in Japan. Intelligent for his species, Splinter was able to learn his master's art by mimicking his movements while he practiced. Yoshi became embroiled in a dispute with a fellow ninja by the name of Oroku Nagi and was eventually murdered by Nagi's brother Oroku Saki.

Without a home, Splinter was forced to run away and live in the New York City sewers. Due to a traffic accident, four baby turtles and a canister of radioactive ooze were sent down into the sewer, where the slime mutated both Splinter and the turtles. Splinter named the four turtles: Leonardo, Donatello, Raphael, and Michelangelo (after a book on Renaissance artists that he found in a storm drain) and trained them in the arts of Ninjutsu, while still raising them as his own sons.

In Teenage Mutant Ninja Turtles issue 10 (volume 4), it would have appeared that this version of Splinter had died of old age. However, as revealed in Teenage Mutant Ninja Turtles issue 32 (volume 4), the Splinter that died was not the Splinter that raised and trained the Turtles.

In issue 26, Splinter's full formal name is revealed to be Hamato Splinter, taking the same Japanese surname as his master Hamato Yoshi.