Teenage Mutant Ninja Turtles started as a comic book and was first published in 1984. Quickly rising to success, within the first decade, they had already released several different types of toys, an animated series, and even a full length feature film.
The story goes that four turtles: Leonardo, Raphael, Donatello, and Michelangelo, were born as normal turtles. After being exposed to radioactive ooze as babies, they developed human traits and decided to use these powers to fight evil in their home of New York City.