Attack of the Giant Leeches (originally to be called The Giant Leeches) is an independently made, 1959 black-and-white science fiction-horror film, produced by Gene Corman and directed by Bernard L. Kowalski. It stars Ken Clark, Yvette Vickers, Bruno VeSota and Jan Shepard. The screenplay was written by Leo Gordon. The film was released by American International Pictures on a double bill with A Bucket of Blood, and was retitled Demons of the Swamp for its UK release. Later, in some areas in 1960, Leeches played on a double bill with the Roger Corman film House of Usher.

Attack of the Giant Leeches was one of a spate of "creature features" produced during the 1950s in response to Cold War fears; a character in the film speculates that the leeches have been mutated to giant size by atomic radiation from nearby Cape Canaveral.