Inferno is a 1980 Italian supernatural horror film written and directed by Dario Argento, and starring Irene Miracle, Leigh McCloskey, Eleonora Giorgi, Daria Nicolodi, and Alida Valli. The plot follows a young man's investigation into the disappearance of his sister, who had been living in a New York City apartment building that also served as a home for a powerful, centuries-old witch. A thematic sequel to Suspiria (1977), it is the second installment of Argento's Three Mothers trilogy. The long-delayed concluding entry, The Mother of Tears, was released in 2007. All three films are partially derived from Thomas de Quincey's 1845 work Suspiria de Profundis, a collection of prose poetry in which he proposes the concept of three "Ladies of Sorrow" (Mater Lachrymarum, Mater Suspiriorum and Mater Tenebrarum), concurrent with the three Fates and Graces in Greek mythology.

The film was internationally co-financed with support from the American studio 20th Century-Fox, who had released Suspiria theatrically in the United States under their "International Classics" banner. Principal photography of Inferno took place largely in studio sets in Rome, though some location shooting also occurred in New York City. 20th Century-Fox released the film in Italy on 8 February 1980, though its release in the United States was shelved for unspecified reasons. In 1986, a year after Fox had issued the film on video in North America, they gave it a limited theatrical release for one week in New York City. Because of its limited release, the film was unable to match the box office success of its predecessor.

While initial critical response was mostly negative, its reputation has improved considerably over the years, and it has been praised for its surreal visual elements and atmosphere, though it has received continued criticism for its incoherent plot. Kim Newman has called it "perhaps the most underrated horror movie of the 1980s." In 2005, the magazine Total Film named Inferno one of the 50 greatest horror films of all time.