The Giant Behemoth (originally titled Behemoth the Sea Monster) is a 1959 British-American monster film directed by Eugène Lourié, with special effects by Willis H. O'Brien, Pete Peterson, Irving Block, Jack Rabin, and Louis de Witt. The film stars Gene Evans and André Morell. The screenplay was written by blacklisted author Daniel Lewis James (under the name "Daniel Hyatt") with director Lourié.

Originally a story about an amorphous blob of radiation, the script was changed at the distributor's insistence to a style similar to The Beast from 20,000 Fathoms (1953), though elements of the original concept remain in the early parts of the film and in the "nuclear-breathing" power of the titular monster.