Prom Night is a 1980 mystery slasher film directed by Paul Lynch, written by William Gray, and starring Leslie Nielsen and Jamie Lee Curtis. The film follows four high school seniors who are targeted at their prom by a masked killer, seeking vengeance for the accidental death of Robin Hammond, a young girl, from six years earlier. The film also stars Casey Stevens, Eddie Benton, Mary Beth Rubens, Michael Tough, Robert A. Silverman, and Antoinette Bower.

Lynch began developing Prom Night after a meeting with Irwin Yablans, producer of Halloween (1978), who suggested he make a horror film similarly centered around a holiday. Instead, Gray wrote a screenplay adapted from a revenge-themed story by Robert Guza Jr.—an acquaintance of Lynch—using a school prom as a unifying setting. A co-production between Canada and the United States, Prom Night was filmed in Toronto in late 1979.

Avco Embassy Pictures released Prom Night on July 18, 1980, in the United States, where it was a significant financial success, breaking weekend box office records in various cities and grossing over $14 million. It was concurrently distributed by Astral Films in Canada, where it was the country's highest-earning horror film that year. Critical reaction to the film was mixed, with some dismissing its depictions of violence against young women, while others alternately praised it for its more subtle onscreen violence. Prom Night received some critical accolades, garnering Genie Award nominations for editing and also for the leading performance of Curtis at the 2nd Genie Awards. An alternative cut of the film was popularly aired on American and Canadian TV networks in 1981, and a soundtrack album was released in Japan the same year by RCA Records.

In the intervening years, Prom Night has accrued a substantial cult following, and has been cited by some film scholars as one of the most influential slasher films of the period. The film has had an extensive home-video release history from numerous distributors across various formats, with its first DVD edition issued by Anchor Bay Entertainment in 1998. A remastered Blu-ray edition of the film was released by Synapse Films in 2014.

In 1974, 11-year-olds Wendy Richards, Jude Cunningham, Kelly Lynch, and Nick McBride play hide-and-seek in an abandoned convent. When 10-year-old Robin Hammond tries to join them, the group scares her, leading to Robin accidentally falling to her death through a window. The children make a pact not to tell anyone what happened in fear of getting in trouble. As the four flee the convent, the shadow of an unseen person who witnessed Robin's death appears.

Six years later, Robin's elder sister, Kim, and fraternal twin brother, Alex, are preparing for the school prom, which falls on the anniversary of Robin's death. Kelly, Jude, and Wendy receive anonymous obscene phone calls, while Nick ignores his ringing phone.

Kim and Nick are now dating. Jude is asked to the prom by goofy jokester Seymour "Slick" Crane. Kelly is going with Drew Shinnick, her boyfriend. Wendy—Nick's ex-girlfriend—asks school bully Lou Farmer to the prom with the purpose of embarrassing Nick and Kim. In the locker room, Kim and Kelly are startled when an unseen assailant shatters a mirror. Later, Wendy, Jude, and Kelly each find their yearbook photos stabbed with a piece of glass. Meanwhile, Kim and Alex's father, school principal Mr. Hammond, learns that Leonard Murch, a sex offender informally blamed for Robin's death, has escaped from a psychiatric facility. Lt. McBride, Nick's father, investigates.

At the prom, a figure wearing a ski mask targets Kelly first, slitting her throat with a mirror shard in the girls' locker room after she rejects Drew's sexual advances. Later, Jude and Slick have sex in his van outside school grounds. The masked killer appears, stabbing Jude in the throat with the mirror shard before causing Slick to drive off a cliff to his death. Meanwhile, while staking out the prom, McBride is informed that the sex offender blamed for Robin's death has been captured.