Macheath is the protagonist and hero of The Threepenny Opera. As the master criminal of London, he commits murders and robberies with aplomb. He is dissatisfied, though, with the small-time criminal life and aspires to middle-class legitimacy. At the opening of the play, he is two weeks away from moving all of his holdings into a bank and turning his gang over to the cops. Macheath does not kill and steal because he is acting out against society; he kills and steals because he is good at it. If he can make money more easily as an honest man, he will do it.

Macheath does not change during the course of the play. At the end he remains a ruthless criminal who cannot see beyond his own self-interest. He never expresses remorse for his crimes, nor does he consider whether he should have done something differently. He always narrowly focuses on his immediate desires and needs.

Macheath possesses many traditional heroic traits: he is sexually appealing, funny, charming, and physically powerful. Throughout the play other characters comment on his charisma. In his actions, though, Macheath is anything but heroic. He is a thief, a murderer, and an adulterer. By making Macheath such an appealing, yet monstrous, character, the question is raised of what makes a person a hero. In the end, Macheath is perhaps best described as an ironic hero.