Planet 51 is a 2009 animated science fiction comedy film directed by Jorge Blanco from a script by Joe Stillman. The film stars Justin Long, Dwayne Johnson, Jessica Biel, Gary Oldman, Seann William Scott and John Cleese, the film follows an astronaut who lands on an alien planet, as one of the aliens helps him return to his ship while evading the military.

An international co-production between Spain, the United Kingdom, and the United States, the film was originally acquired for North American distribution by New Line Cinema, but then sold to Sony Pictures before completion. Originally titled Planet One, and later named as an allusion to Area 51, the film was completed on a $70 million budget, which, at the time of its release, was the most expensive film produced in Spain.

Planet 51 was released on 20 November 2009, in the United States and Canada by Sony Pictures Releasing's TriStar Pictures and Remstar Media Partners respectively, on 27 November in Spain by DeAPlaneta Distribución, and 4 December in the United Kingdom by HandMade Films International. The film grossed $105.6 million in the worldwide box office. It received generally negative reviews from critics, but earned the Goya Award for Best Animated Film in Spain.