"Mack the Knife" (originally "Die Moritat von Mackie Messer") is a theatrical ballad composed by Kurt Weill with lyrics by Bertolt Brecht, written in 1928 as a last-minute addition to their landmark work The Threepenny Opera. The song was inserted at the insistence of actor Harald Paulsen, who played the criminal antihero Macheath and demanded a more dramatic character introduction. Weill and Brecht reassigned it to a street singer in the tradition of the Moritat, a medieval form of murder ballad performed by wandering minstrels recounting gruesome crimes with ironic detachment. Kurt Gerron sang it at the Berlin premiere, where a barrel organ was intended to accompany the performance but broke down, forcing the pit jazz band to step in instead. The piece draws on John Gay's 1728 The Beggar's Opera and its highwayman Macheath, itself inspired by real-life thief Jack Sheppard, but Weill and Brecht sharpened the satire into a critique of capitalism and crime amid Weimar Germany's social upheaval. The tune remained relatively obscure outside theater circles until the mid-1950s, when Louis Armstrong's 1955 vocal recording brought it into the jazz mainstream, reaching number 20 on the Billboard chart despite facing radio bans for allegedly glorifying crime. Bobby Darin's up-tempo 1959 rendition became one of the decade's biggest pop hits, holding the number one spot for nine weeks. Ella Fitzgerald's celebrated 1960 live version, in which she forgot the lyrics and improvised a scat performance, added another chapter to its legacy. Sonny Rollins recorded a definitive jazz instrumental reading on his 1956 album Saxophone Colossus, establishing the tune as a vehicle for extended improvisation.