Dog Day Afternoon is a 1975 American biographical crime drama film directed by Sidney Lumet and produced by Martin Bregman and Martin Elfand. The film stars Al Pacino, John Cazale, James Broderick, and Charles Durning. The screenplay is written by Frank Pierson and is based on the Life magazine article "The Boys in the Bank" by P. F. Kluge and Thomas Moore. The feature chronicled the 1972 robbery and hostage situation led by John Wojtowicz and Salvatore Naturile at a Chase Manhattan branch in Brooklyn.

Elfand brought Bregman's attention to the article, who proceeded to negotiate a deal with Warner Bros. and clear the rights to use the story. Pierson conducted his research and wrote a script that centered the story of the robbery around Wojtowicz. The cast was selected by Lumet and Pacino, with the latter selecting past co-stars from his Off-Broadway plays. Filming took place between September and November 1974, and the production was finished three weeks ahead of schedule.

Upon theatrical release on September 21, 1975, Dog Day Afternoon was a critical and box office success. The film was nominated for seven Golden Globe Awards and six Academy Awards (including Best Picture) and won the Academy Award for Best Original Screenplay. In 2009, Dog Day Afternoon was deemed "culturally, historically, or aesthetically significant" by the Library of Congress, and was selected for preservation in the National Film Registry.