Teenage Mutant Ninja Turtles

Television reporter April O'Neil, investigating a crime wave terrorizing New York City, is attacked by thieves, but is saved by an unseen group of vigilantes, the Teenage Mutant Ninja Turtles - Leonardo, Donatello, Michelangelo, and Raphael. However, Raphael lost a sai in the fight, which April recovered. The turtles return to their hidden lair in the sewer, where their adoptive father, a rat named Splinter, advises them to continue practicing the art of ninjutsu. Visiting the surface, Raph watches Critters, only to come to blows with fellow vigilante Casey Jones, and is counseled by Splinter.

Charles Pennington, April's supervisor at Channel 3 News, struggles to control his delinquent son Danny, who has been recruited with other troubled teenagers to help the mysterious ninja Foot Clan in their wave of thefts. April suspects the Foot are responsible for the crime spree, raising the ire of Police Chief Sterns, while Shredder, leader of the Foot, sends his soldiers after April. Raph defeats them and brings the unconscious April to the turtles' lair, unknowingly followed by a Foot soldier. Splinter explains to April that he and the turtles were mutated into intelligent, anthropomorphic creatures by a mysterious chemical. After escorting April home and bonding over their love of pizza, the turtles return to find their lair ransacked and Splinter kidnapped, and return to April's apartment.

Danny is arrested, which Sterns uses to pressure Charles, who urges April to drop her investigation. Glimpsing the turtles hiding at April's apartment, Danny informs Shredder at the Foot's hideout, where Splinter is being held prisoner. Back at April's place, Raph argues with Leo over his leadership, and is ambushed on the rooftops by the Foot and beaten unconscious. Casey witnesses this and aids the turtles in fighting off the Foot and escape the burning building with April, who is fired by Charles in a phone message. Danny seeks counsel from the captive Splinter, and flees the Foot Clan. The turtles retreat to April's rundown family farm upstate, where she bonds with Casey as Raph recovers. Leo receives a vision of Splinter and assembles the other turtles to contact him through astral projection. Splinter delivers his final lesson, inspiring the turtles to return to the city.

The turtles find Danny hiding in their lair, and Casey follows him to the Foot's hideout. Splinter tells Danny that as an ordinary pet in Japan, he learned ninjutsu from watching his master, the ninja Hamato Yoshi. To escape conflict with his rival, Oroku Saki, over the love of a woman, Tang Shen, Yoshi fled with Shen to New York, where they were killed by a vengeful Saki. Splinter suggests Saki is linked to the Foot, while Shredder finds Danny and realizes that the turtles have returned, ordering Splinter to be killed. Casey and Danny free Splinter and defeat Shredder's lieutenant Tatsu, before convincing the remaining Foot members that they have been manipulated by Shredder.

The turtles repel the Foot from their lair and onto the streets, before confronting the spear-wielding Shredder on a rooftop. After a fierce battle, Shredder claims that Splinter is dead, overpowering an infuriated Leo and disarming the turtles. Before Shredder can kill Leo, Splinter appears and identifies him as Oroku Saki, who in turn recognizes Splinter as Yoshi's pet rat. Shredder charges Splinter, who snares his spear with Mikey's nunchaku, leaving Shredder dangling over the roof's edge. Shredder makes a final attempt to kill Splinter with a thrown tanto, but Splinter drops him into a garbage truck below. Casey "accidentally" activates the truck's compactor, crushing Shredder.

The police arrive to arrest the Foot soldiers, and recover the stolen goods from their hideout. The Channel 3 news crew arrives as well to cover the story, and Danny is reunited with Charles, who gives April her job back with major benefits. April and Casey share a kiss, while the turtles celebrate their victory with Splinter.

On the film's initial release, Roger Ebert gave 2.5 out of 4 stars and concluded it to be "nowhere near as bad as it might have been, and probably is the best possible Teenage Mutant Ninja Turtle movie. It supplies, in other words, more or less what Turtle fans will expect". Ebert singled out the production design, which he described as a "low-rent version of Batman or Metropolis." Variety praised the film's tongue-in-cheek humor and "amusingly outlandish" martial arts sequences, but thought it was "visually rough around the edges" and "sometimes sluggish in its plotting". Janet Maslin of The New York Times criticized the cinematography, stating that it was so "poorly photographed that the red-masked turtle looks almost exactly like the orange-masked one". Kim Newman wrote in the Monthly Film Bulletin that he found the characters reminiscent of the early 1970s Godzilla film series, describing the turtles as "loveable monsters in baggy foam rubber suits" who "befriended lost children and smashed things up in orgies of destruction that somehow never hurt anyone" and "drop the occasional teenage buzzword but are never remotely convincing as teenagers, mutants, ninjas or turtles".

Variety, the New York Times, and the Monthly Film Bulletin all noted the Asian villains of the film; Variety described "overtones of racism in its use of Oriental villains", while Maslin stated "the story's villainous types are Asian, and the film plays the yellow-peril aspects of this to the hilt". Newman noted a racist joke in April O'Neil's response to the Foot Clan, "What's the matter, did I fall behind on my Sony payments?", finding that the film expressed a "resentment of Japan's economic strength even while the film is plundering Japan's popular culture". Ebert felt there was "no racism" in the film.

Lloyd Bradley of Empire gave the film four out of five stars, stating: "A well-rounded, unpretentious, very funny, knockabout adventure - subtly blended so that it's fun for all the family". Owen Gleiberman, writing for Entertainment Weekly, gave an F rating, finding that none of the four turtles or Splinter had any personality, but felt that a young audience might enjoy the film, noting he might have "gone for it too had I been raised on Nintendo games and the robotic animation that passes for entertainment on today's Saturday-morning TV".

Entertainment Weekly and The New York Times praised the work of Jim Henson's Creature Shop, with Maslin stating "without which there would have been no film at all".

A second film, Teenage Mutant Ninja Turtles II: The Secret of the Ooze, was released in 1991. With a rushed production and a lighter tone, it received weaker reviews and was less successful at the box office. Teenage Mutant Ninja Turtles III (1993) was aimed at the Japanese market, the largest foreign market for US films at the time, but failed to see release there and had weaker reviews and sales.