The Manhattan Project is a 1986 American science fiction thriller film. Named after the World War II-era program that constructed the first atomic bombs, the plot revolves around a gifted high school student who decides to construct an atomic bomb for a national science fair. It was directed by Marshall Brickman, based upon his screenplay co-written with Thomas Baum, and starred Christopher Collet, John Lithgow, John Mahoney, Jill Eikenberry and Cynthia Nixon. This film – a box-office bomb whose ticket sales recovered just 21 percent of its budget – was the first from the short-lived Gladden Entertainment.

The film's director and screenplay co-writer Marshall Brickman had established his career as a co-writer on several Woody Allen films. The Manhattan Project was his third film as director, following the comedies Simon (1980) and Lovesick (1983).