Insomnia is a 2002 American psychological thriller film directed by Christopher Nolan and written by Hillary Seitz. It is the only film directed by Nolan that he did not write or co-write. A remake of the 1997 Norwegian film of the same name, it stars Al Pacino, Robin Williams and Hilary Swank with Maura Tierney, Martin Donovan, Nicky Katt and Paul Dooley in supporting roles.

The film follows two Los Angeles homicide detectives investigating the murder of a teenage girl in Nightmute, Alaska. After the killer witnesses an accidental shooting committed by one of the detectives, they create a plan for both parties to mutually avoid prosecution.

Insomnia premiered at the Tribeca Festival on May 3, 2002, and was theatrically released in the United States on May 24, 2002. It grossed $114 million worldwide against a production budget of $46 million. The film received critical praise, particularly for Pacino's and Williams' performances. At the 29th Saturn Awards, Williams was nominated for Best Supporting Actor, and Seitz was nominated for Best Writing.

Insomnia would be the last film directed by Nolan to receive an R-rating from the Motion Picture Association of America until the release of Oppenheimer in 2023.