Teenage Mutant Ninja Turtles II: The Secret of the Ooze is a 1991 American superhero action comedy film. It is based on the Teenage Mutant Ninja Turtles characters created by Kevin Eastman and Peter Laird, and is directed by Michael Pressman and written by Todd W. Langen. It is the sequel to Teenage Mutant Ninja Turtles (1990) within the original Turtles film trilogy. It stars Paige Turco and David Warner, with the voices of Brian Tochi, Robbie Rist, Adam Carl, and Laurie Faso. Resuming from the events of the first film, the Shredder returns at command of the Foot Clan for revenge on the Turtles. When he learns the secret behind the Turtles' mutation, he becomes more dangerous than ever. The film reveals the origins of Splinter and the Turtles and introduces two new villains, Tokka and Rahzar. Unlike the first film, the Turtles mostly fight bare-fisted, to tone down the violence.

The film is dedicated to Muppets creator Jim Henson, who died less than one year before release. Jim Henson's Creature Shop created the animatronic creature costumes for these first two films.

The film was released theatrically in the United States on March 22, 1991, by New Line Cinema. It received mixed to negative reviews from critics, who said it departed from the much darker tone of the original 1990 film. However, it was financially successful, grossing $78.7 million against a budget of $25 million, becoming the thirteenth highest-grossing film domestically in the year of its release. A sequel, Teenage Mutant Ninja Turtles III, was released in 1993.