The Teenage Mutant Ninja Turtles (or simply Ninja Turtles, an previously known in the United Kingdom as Teenage Mutant Hero Turtles) are a fictional team of four turtle mutants, who are trained by their sensei, Master Splinter, to become skilled Ninja warriors. From their home in the sewers of Manhattan, they battle petty criminals, evil megalomaniacs, and alien invaders, all while remaining isolated from society at large. The characters also initially appeared in comic books before being licensed for toys, cartoons and film adaptations.