Teenage Mutant Ninja Turtles, sometimes abbreviated to TMNT, is an American media franchise created by the comic book artists Kevin Eastman and Peter Laird. It follows Leonardo, Michelangelo, Donatello and Raphael, four anthropomorphic turtle brothers trained in ninjutsu who fight evil in New York City. Supporting characters include the turtles' rat sensei Splinter, their human friends April O'Neil and Casey Jones, and enemies such as Baxter Stockman, Krang, and their archenemy, the Shredder.

The franchise began as a comic book, Teenage Mutant Ninja Turtles, which Eastman and Laird conceived as a parody of elements popular in superhero comics at the time. The first issue was published in 1984 by Eastman and Laird's company Mirage Studios and was a surprise success. In 1987, Eastman and Laird licensed the characters to Playmates Toys, which developed a line of Turtles action figures. About US$1.1 billion of Turtles toys were sold between 1988 and 1992, making them the third-bestselling toy figures ever at the time.

The action figures were promoted with an animated series, which premiered in 1987 and ran for almost a decade. Three live-action films were released; the first, released in 1990, became the highest-grossing independent film up to that point. Numerous video games have also been released, including several developed by Konami. In some European regions, the franchise was titled Teenage Mutant Hero Turtles due to the violent connotations of the word "ninja".

Eastman sold his share of the Turtles franchise to Laird in 2000. In 2009, Laird sold it to Viacom, now Paramount Global. Viacom commissioned a new comic series, two new live-action films, and new animated series.