Alligator

Alligator is a 1980 American independent comedy horror film directed by Lewis Teague and written by John Sayles. It stars Robert Forster, Robin Riker and Michael V. Gazzo. It also includes an appearance by actress Sue Lyon in her last screen role. Set in Chicago, the film follows a police officer and a reptile expert who track an enormous, ravenous man-eating alligator flushed down the toilet years earlier, that is attacking residents after escaping from the city's sewers.