Weill, vyl or wyl, Kurt (1900-1950), was a German composer famous for his music for the theater. Weill is noted for music he wrote for the plays of the German playwright Bertolt Brecht. The best-known work by Brecht and Weill is The Threepenny Opera (1928), which includes the popular song "Mack the Knife." They also wrote Happy End (1929), The Rise and Fall of the City of Mahagonny (1930), and The Seven Deadly Sins (1933).