The Mercury Theatre on the Air is a radio series of live radio dramas created and hosted by Orson Welles. The weekly hour-long show presented classic literary works performed by Welles's celebrated Mercury Theatre repertory company, with music composed or arranged by Bernard Herrmann. The series began July 11, 1938, as a sustaining program on the CBS Radio network, airing Mondays at 9 pm ET. On September 11, the show moved to Sundays at 8 pm.

George Orson Welles was an American director, actor, writer, producer, and magician who is remembered for his innovative work in film, radio, and theatre. He is considered to be among the greatest and most influential filmmakers of all time.