Mack is a lieutenant of the Smithy Gang and the boss of the first chapter of Super Mario RPG: Legend of the Seven Stars. Mack  commands an army of Shysters and can use fire magic. Like the other members of the Smithy Gang, Mack is modeled after a weapon (in his case, a knife) and he is named after the song "Mack the Knife"

With his Shysters, Mack attacked the Mushroom Kingdom while Mario was in Bandit's Way. Mack occupied the throne room of the Mushroom Castle while his Shysters terrorized the residents of the surrounding town.

After returning to town, Mario and Mallow fought their way to the throne room and defeated Mack. Following Mack's defeat, the two remaining Shysters left to inform Smithy of Mack's destruction. 

Mack would return in Smithy's Factory, in the form of a gray mass-produced copy of the original.

In the parade, Mack, along with Bowyer and Yaridovich, is seen being pounded by Smithy's hammer.