Castle Keep is a 1969 American war comedy-drama film combining surrealism with tragic realism. It was directed by Sydney Pollack, and starred Burt Lancaster, Patrick O'Neal, Jean-Pierre Aumont, Bruce Dern and Peter Falk. The film appeared in the summer of 1969, a few months before the premiere of Pollack's smash hit They Shoot Horses, Don't They?

The film is based on the novel of the same name by William Eastlake published in 1965, and according to New York Times critic Vincent Canby “accomplishes the dubious feat of being both anti and pro war at the same time”. Eastlake enlisted in the United States Army in 1942. He served in the Infantry for four and a half years, and was wounded while leading a platoon during the Battle of the Bulge.