Monkey Shines (also known as Monkey Shines: An Experiment in Fear) is a 1988 American science fiction psychological horror film written and directed by George A. Romero and starring Jason Beghe, Kate McNeil, John Pankow, and Joyce Van Patten. Its plot follows a young athlete who becomes a paralyzed quadriplegic, and develops a bond with an intelligent service monkey named "Ella" who becomes homicidal after she is injected with an experimental serum of human brain tissue. It is based on the 1983 British novel of the same title by Michael Stewart.

Producers Peter Grunwald and Charles Evans of Orion Pictures acquired the rights to Stewart's novel in 1985, and began production two years later, with Romero assigned to direct. The film marked Romero's first major studio feature, and was his second-most expensive film at that time, with a budget of $7 million. The setting was changed from Oxford, England, where the novel was set, to Pittsburgh, Pennsylvania, a city in which Romero had long resided and often set his films. Principal photography of Monkey Shines took place in Pittsburgh in the late summer and early fall of 1987. It had a protracted post-production and editing process, as Romero shot more film than he had on any of his previous projects, particularly due to the use of live monkeys.

Monkey Shines was released theatrically by Orion Pictures in July 1988, receiving mixed reviews and a lackluster box-office reception, grossing $5.3 million against its $7 million budget. In the intervening years, the film has been noted by critics as an offbeat entry in Romero's filmography, and has earned status as a minor cult film.