The Teenage Mutant Ninja Turtles (TMNT or Ninja Turtles) are a fictional team of four anthropomorphic turtles, 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 TMNT originated in an American comic book published by Mirage Studios in 1984. The concept arose from a comical sketch by Kevin Eastman during a casual evening of brainstorming]] with his friend Peter Laird. Using money from a tax refund together with a loan from Eastman's uncle, the young artists self-published a single-issue comic intended to parody two of the most popular comics of the early 1980s: Marvel Comics' The New Mutants, which featured teenage mutants, and Daredevil, which featured ninja clans dueling for control of the New York City underworld.

Much of the Turtles' mainstream success is owed to Mark Freedman, a licensing agent who sought out Eastman and Laird to propose wider merchandising opportunities for the offbeat property. In January 1987, they visited the offices of Playmates Toys, a small California toy company who wished to expand into the action figure market. Accompanied by the popular Teenage Mutant Ninja Turtles animated series, the TMNT were soon catapulted into pop culture history. At the height of the frenzy, the Turtles' likenesses could be found on a wide range of children's merchandise, from PEZ dispensers to skateboards, breakfast cereal, and school supplies.

Today, there is a resurgence in the Turtles' popularity with the success of the recent animated series, a new line of Playmates action figures, Konami video games, and a new computer-animated feature film in production for a 2007 release.