Kurt Weill (1900–1950) was a German-American composer who revolutionized 20th-century musical theater, best known for his collaborative work with Bertolt Brecht, including The Threepenny Opera (“Mack the Knife”). Son of a cantor, he studied under Ferruccio Busoni in Berlin, producing avant-garde works before embracing a simpler, socially critical style. Fleeing Nazi Germany in 1933, he moved to Paris and then to the U.S. in 1935, where he adapted to Broadway with hits like Lady in the Dark and Lost in the Stars.