Back to the Future is a 1985 (1985 in film) American (Cinema of the United States) science fiction (Science Fiction film) adventure (Adventure film) comedy (Comedy film) film directed by Robert Zemeckis, written by Zemeckis and Bob Gale, and produced by Gale and Neil Canton, with Steven Spielberg, Kathleen Kennedy (Kathleen Kennedy (film producer)) and Frank Marshall (Frank Marshall (film producer)) serving as executive producers. The film stars Michael J. Fox, Christopher Lloyd, Lea Thompson, Crispin Glover and Thomas F. Wilson. Back to the Future tells the story of Marty McFly, a teenager who is accidentally sent back in time from 1985 to 1955. He meets his parents in high school, accidentally attracting his mothers romantic interest. Marty must repair the damage to history by causing his parents to fall in love, while finding a way to return to 1985.

Zemeckis and Gale wrote the script after Gale mused upon whether he would have befriended his father if they attended school together. Various film studios rejected the script until the box office success of Zemeckis Romancing the Stone, and the project was set up at Universal Pictures (Universal Studios) with Spielberg as an executive producer. Eric Stoltz was originally cast as Marty McFly when Michael J. Fox declined as he was busy filming the TV series Family Ties. However, during filming Stoltz and the filmmakers decided that Stoltz was miscast, so they asked Fox again and he managed to work out a timetable in which he could give enough time and commitment to both; the subsequent recasting meant the crew had to race through reshoots and post-production to complete the film for its July 3, 1985 release date.

When released, Back to the Future became the most successful film of the year, grossing more than $380 million worldwide and receiving critical acclaim. It won the Hugo Award for Best Dramatic Presentation and the Saturn Award for Best Science Fiction Film, as well as Academy Awards, and Golden Globe (Golden Globe Awards) nominations among others. Ronald Reagan even quoted the film in the 1986 State of the Union Address. In 2007, the Library of Congress selected it for preservation in the National Film Registry, and in June 2008 the American Film Institutes special AFIs 10 Top 10 acknowledged the film as the 10th best film in the science fiction genre. The film marked the beginning of a franchise (Back to the Future (film series)), with Back to the Future Part II and Back to the Future Part III released back-to-back in 1989 and 1990, as well as an animated series (Back to the Future: The Animated Series) and theme park ride (Back to the Future: The Ride).