Splinter

Splinter is the mutant rat sensei who trained Leonardo, Donatello, Raphael, and Michelangelo in ninjutsu. Once the pet of ninja master Hamato Yoshi, he learned martial arts by mimicking his owner, then mutated into a humanoid rat and became the Turtles' surrogate father and teacher.

Few characters in comics carry the quiet gravity of Splinter, the wise sensei whose presence anchors the world of the Teenage Mutant Ninja Turtles from the very beginning. Born from the wildly inventive minds of Peter Laird and Kevin Eastman, he made his debut in the landmark 1985 fourth printing of Teenage Mutant Ninja Turtles #1 — a Bronze Age publication from Mirage Studios that has since become one of the most celebrated key issues in independent comics history. Across nearly four decades of stories stretching from 1985 all the way to 2024, Splinter has shared the page with Leonardo, Donatello, Raphael, Michaelangelo, and April O'Neil, remaining a constant, steadying presence amid the chaos of their adventures — even turning up in the unlikely crossover Teenage Mutant Ninja Turtles X Stranger Things. If you're exploring the rich, scrappy origins of one of comics' most beloved independent franchises, Splinter is absolutely essential company.