Fort Apache is a 1948 American Western film directed by John Ford and starring John Wayne and Henry Fonda. The film was the first of the director's "Cavalry Trilogy" and was followed by She Wore a Yellow Ribbon (1949) and Rio Grande (1950), both also starring Wayne.

The screenplay was inspired by James Warner Bellah's short story "Massacre" (1947). The historical sources for "Massacre" have been attributed both to George Armstrong Custer's Battle of Little Bighorn and to the Fetterman Fight, with the character of Col. Thursday being very similar in story and appearance to that of Lt. Howard B. Cushing. The film was one of the first to present an authentic and sympathetic view of Native Americans.

In his review of the DVD release of Fort Apache in 2012, The New York Times movie critic Dave Kehr called it "one of the great achievements of classical American cinema, a film of immense complexity that never fails to reveal new shadings with each viewing" and "among the first 'pro-Indian' Westerns" in its portrayal of indigenous Americans with "sympathy and respect".

The film was awarded the Best Director and Best Cinematography awards by the Locarno International Film Festival of Locarno, Switzerland. Screenwriter Frank S. Nugent was nominated for best screenplay by the Writers Guild of America.

A stagecoach races across the Southwestern desert, carrying widower Lieutenant Colonel Owen Thursday and his daughter, Philadelphia, to his new posting at Fort Apache, an isolated U.S. cavalry post on the Arizona frontier. Thursday is impatient and full of complaints, revealing little understanding of the country. A West Point graduate who was brevetted a general during the Civil War, he has been serving in Europe for several years and is full of resentment at being recalled and “shunted aside” to what he considers a career-ending assignment.

At a waystation, they meet newly minted graduate Second Lieutenant Michael O'Rourke on his way to Fort Apache. Four sergeants arrive with a vehicle to meet Michael, which irks Thursday. The sergeants notice that Michael and Philadelphia are attracted to each other. They arrive at Fort Apache during the Washington's Birthday dance. Philadelphia dances with acting commander Captain Kirby York. York commanded his own regiment during the Civil War and has learned the ways of the Apache. Michael has a touching reunion with his parents.

The next morning at officers call, Thursday assumes command and criticizes them all—except for Michael—for being improperly dressed, revealing a by-the-book approach that soon establishes him as a martinet. When York tries to brief him on the realities of life at Fort Apache, Thursday dismisses Native Americans as “digger Indians”.

Michael is the son of highly regarded Sergeant Major Michael O'Rourke, the post's ranking non-commissioned officer. The elder O'Rourke was a major in the Irish Brigade during the Civil War and earned the Medal of Honor, entitling his son to enter West Point and be commissioned an officer. Thursday is taken aback by this revelation.