Mac Heath - first name, if any, unknown, unless it actually is Mac - also known as Mac the Knife, was an almost completely amoral rogue, robber, murderer, rapist, arsonist and highwayman. He was the main character of the 'Three-Penny Opera' and its older predecessor, the 'Beggar's Opera'; he's most famous, or infamous, from the song 'Mac the Knife', in which he is portrayed a good deal less heinous than the German original, 'Die Moritat von Messer Mackie'.
Little is known about Mac Heath, except that he killed, raped and stole with impunity. He was the head member of a criminal gang in Elizabethan London.
Mac Heath's fate was sealed when he against all odds, fell in love with Polly Peachum, daughter of the 'Beggar King' and was prepared to give up his life of crime. Incensed with jealousy, the other women he had been with turned him in to the authorities for the reward on his head. Moments before he would be executed at Tyburn Hill, the demands of a happy ending necessary for the opera to work properly got him not only pardoned by the Queen, but even bestowed a title and an estate.