Marcus Samuel Blitzstein, better known as Marc Blitzstein (March 2, 1905 – January 22, 1964), was an American composer. He won national attention in 1937 when his pro-union musical The Cradle Will Rock, directed by Orson Welles, was shut down by the Works Progress Administration. He is known for The Cradle Will Rock and for his Off-Broadway translation/adaptation of The Threepenny Opera by Bertolt Brecht and Kurt Weill. His works also include the opera Regina, an adaptation of Lillian Hellman's play The Little Foxes; the Broadway musical Juno, based on Seán O'Casey's play Juno and the Paycock; and No for an Answer. He completed translation/adaptations of Brecht's and Weill's musical play Rise and Fall of the City of Mahagonny and of Brecht's play Mother Courage and Her Children with music by Paul Dessau. Blitzstein also composed music for films, such as Surf and Seaweed (1931) and The Spanish Earth (1937), and he contributed two songs to the original 1960 production of Hellman's play Toys in the Attic.