1900 (Italian: Novecento, "Twentieth Century") is a 1976 epic historical drama film directed by Bernardo Bertolucci, and featuring an international ensemble cast including Robert De Niro, Gérard Depardieu, Dominique Sanda, Francesca Bertini, Laura Betti, Stefania Casini, Ellen Schwiers, Sterling Hayden, Alida Valli, Romolo Valli, Stefania Sandrelli, Donald Sutherland and Burt Lancaster. Set in Bertolucci's ancestral region of Emilia, Italy, the film chronicles the lives and friendship of two men—the landowning Alfredo Berlinghieri (De Niro) and the peasant Olmo Dalcò (Depardieu)—as they witness and participate in the political conflicts between fascism and communism that took place in Italy in the first half of the 20th century. The film premiered out of competition at the 1976 Cannes Film Festival.

With a runtime of 317 minutes in its original version, 1900 is known for being one of the longest commercially released films in history. Its great length led to it being presented in two parts when originally released in many countries, including Italy, East and West Germany, Denmark, Belgium, Norway, Sweden, Colombia, Pakistan and Japan. In other countries, including the United States, a single edited version of the film was released. 1900 has become widely regarded as a cult classic, and has received several special-edition home-video releases from a variety of distributors. A restoration of the film premiered out of competition at the 74th Venice International Film Festival in 2017.

In 2008, the film was included on the Italian Ministry of Cultural Heritage's 100 Italian films to be saved, a list of 100 films that "have changed the collective memory of the country between 1942 and 1978".