K-9 is a 1989 motion picture comedy starring James Belushi and Mel Harris.

Belushi plays "maverick" police detective Michael Dooley, who has been tagged for execution by a major international drug dealer (Lyman, played by Kevin Tighe). To help, a so-called "friend" (Brannigan, played by Ed O'Neill) gives Dooley a police dog, "Jerry Lee," trained to sniff drugs. The two attempt to put Lyman in prison, but Dooley soon learns that Jerry Lee is a mischievous smart-alec who works only when he wants to. Many of the movie's gags revolve around Jerry Lee's playfully destructive episodes.

The German Shepherd Dog "Jerry Lee" was played by Koton, a real-life police dog from the Kansas City, Missouri police department. In 1991, Koton was shot and killed while trying to apprehend a suspect in the murder of a police officer. Ten days before his death, Koton found ten kilos of cocaine worth more than $US 1.2 million.

K-9 was directed by Rod Daniel and written by Steven Siegel and Scott Myers. It was produced by Lawrence Gordon and Charles Gordon, and released by Universal City Studios. It has two sequels, K-911 (1999) and K-9: P.I. (2002).