The Imaginarium of Doctor Parnassus is a 2009 fantasy film directed by Terry Gilliam and written by Gilliam and Charles McKeown. The film follows a travelling theatre troupe whose leader, having made a bet with the Devil, takes audience members through a magical mirror to explore their imaginations and present them with a choice between self-fulfilling enlightenment or gratifying ignorance.

The film stars Heath Ledger, Christopher Plummer, Verne Troyer, Andrew Garfield, Lily Cole, Tom Waits, Johnny Depp, Colin Farrell, and Jude Law, though Ledger's death one-third of the way through filming caused production to be temporarily suspended. Ledger completed most of the movie's runtime, and then his role was recast with Depp, Law, and Farrell portraying transformations of his character as he travels through a dream world. The film is Ledger's final performance; it was dedicated to him and co-producer William Vince.

Its world premiere was during the 62nd Cannes Film Festival, out of competition. The film, which cost $30 million to make, grossed more than $60 million in its worldwide theatrical release.

It was nominated for two Academy Awards. The first was Best Art Direction with art directed by Dave Warren and Anastasia Masaro, and set decorated by Caroline Smith; and it lost to Avatar. The second was Best Costume Design with costumes designed by Monique Prudhomme; and it lost to The Young Victoria.