A Life in the Theatre is a 1977 play by David Mamet.  It focuses on the relationship between two actors, the play's only characters. One, Robert, is a stage veteran while John is a young, promising actor. As the play goes on they are involved in a variety of productions, and gradually their relationship begins to change.

The play premiered Off-Broadway at the Lucille Lortel Theatre (then the Theatre De Lys) in October 1977 through July 1978, with Ellis Rabb as Robert and Peter Evans as John and directed by Gerald Gutierrez.