Back to the Future Part III is a 1990 American science fiction Western film and the third installment of the Back to the Future trilogy. The film was directed by Robert Zemeckis, and stars Michael J. Fox, Christopher Lloyd, Mary Steenburgen, Thomas F. Wilson, and Lea Thompson. The film continues immediately following Back to the Future Part II (1989); while stranded in 1955 during his time travel adventures, Marty McFly (Fox) discovers that his friend Dr. Emmett "Doc" Brown (Lloyd), trapped in 1885, was killed by Buford "Mad Dog" Tannen (Wilson), Biff's great-grandfather. Marty travels to 1885 to rescue Doc and return once again to 1985, but matters are complicated when Doc falls in love with Clara Clayton (Steenburgen).

Back to the Future Part III was filmed in California and Arizona, and was produced on a $40 million budget back-to-back with Part II. Part III was released in the United States on May 25, 1990, six months after the previous installment, and grossed $245 million worldwide during its initial run, making it the sixth-highest-grossing film of 1990. The film received a positive response from critics, who noted it as an improvement over Part II.