The Beginning or the End is a 1947 American docudrama film about the development of the atomic bomb in World War II, directed by Norman Taurog, starring Brian Donlevy, Robert Walker, and Tom Drake, and released by Metro-Goldwyn-Mayer. The film dramatizes the creation of the atomic bomb in the Manhattan Project and the bombing of Hiroshima.

The film originated in October 1945 as a project of actress Donna Reed and her high school science teacher, Edward R. Tompkins, who was a chemist at the Oak Ridge National Laboratory. Bob Considine wrote the treatment, which was sent to MGM scriptwriters. The title was supplied by President Harry S. Truman. At the time there was a legal requirement that permission be obtained to depict living well-known public figures. Many refused, but others, such as J. Robert Oppenheimer, co-operated. Major General Leslie R. Groves, Jr., the director of the Manhattan Project, was hired as a consultant for $10,000 (equivalent to $156,000 in 2023).

Although the filmmakers put considerable effort into historical accuracy, particularly in details, the film is known for some key distortions of history. An entirely fictional sequence was added in which Truman agonizes over whether to authorize the attack; anti-aircraft shells are shown bursting around the Enola Gay on its bombing run over Hiroshima. The film received generally mixed reviews, and was a box office disappointment.