The Evil Dead is a 1981 American independent supernatural horror film written and directed by Sam Raimi (in his feature directorial debut). The film stars Bruce Campbell, Ellen Sandweiss, Richard DeManincor, Betsy Baker, and Theresa Tilly as five college students vacationing in an isolated cabin in the woods, where they find an audio tape that, when played, releases a legion of demons and spirits. Four members of the group suffer from demonic possession, forcing the fifth member, Ash Williams (Campbell), to survive an onslaught of increasingly gory mayhem.

Raimi, Campbell, producer Robert G. Tapert, and their friends produced the 1978 short film Within the Woods as a proof of concept to build the interest of potential investors, which secured US$90,000 to begin work on The Evil Dead. Principal photography took place on location in a remote cabin in Morristown, Tennessee, in a filming process that proved extremely uncomfortable for the cast and crew. The film's extensive prosthetic makeup and stop-motion effects were created by artist Tom Sullivan. The completed film had its world premiere at the Redford Theatre in Detroit on October 15, 1981, and attracted the interest of producer Irvin Shapiro, who helped screen the film at the 1982 Cannes Film Festival. Horror author Stephen King gave a rave review of the film, which resulted in New Line Cinema acquiring its distribution rights and giving it a wide theatrical release on April 15, 1983.

The Evil Dead grossed $2.4 million in the United States and between $2.9 and $29.4 million worldwide. Both early and later critical reception were universally positive; in the years since its release, the film has developed a reputation as one of the most significant cult classics, having been cited among the greatest horror films of all time, and one of the most successful independent films. It launched the careers of Raimi, Tapert, and Campbell, who have continued to collaborate on several films together, such as Raimi's Spider-Man trilogy.

The Evil Dead spawned a media franchise, beginning with two direct sequels written and directed by Raimi, Evil Dead II (1987) and Army of Darkness (1992), a fourth film, Evil Dead (2013), which serves as a soft reboot and continuation, a follow-up television series, Ash vs Evil Dead, which aired from 2015 to 2018, and a fifth film, Evil Dead Rise (2023); the franchise also includes video games and comic books. The film's protagonist Ash Williams is considered to be a cultural icon.