Monster in a Box is a monologue originally performed live on stage by the writer Spalding Gray then subsequently made into a 1992 film starring Gray and directed by Nick Broomfield.A follow-up to Gray's earlier work, Swimming to Cambodia, the work consists of a long-form monologue by Gray detailing the trials and tribulations he encountered while writing his first novel, Impossible Vacation (the titular "monster"). He also relates the sudden fame afforded him after the release of Swimming to Cambodia.

The soundtrack for the film was composed by Laurie Anderson.

An extended version of the monologue was published in book form prior to the release of the film.