Mack

Mack is a member of the Smithy Gang and one of Smithy's lieutenants. He appeared in the game Super Mario RPG: Legend of the Seven Stars. Mack is in command of an army of Shysters, pogo-stick riding Shy Guys. Mack also wields powerful fire magic. With his army of soldiers, Mack attacked the Mushroom Kingdom and occupied it. Mario, conveniently, was in Bandit's Way with Mallow, chasing down the thief Croco. Mack allowed his Shysters to overrun the town, causing chaos as they wished.

When Mario and Mallow returned to town, they were shocked by the sudden appearance of the Shysters. Together, they rescued townspeople and fought to the throne room of the castle, where they confronted Mack and his elite Shyster Bodyguards. After a long battle, Mario emerged victorious, driving Smithy's forces out of the Mushroom Kingdom. In the aftermath, Mario earned his first Star Piece.

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

Mack appears to be a large knife with eyes. However, there is also a red-colored creature on top of the knife. It is unknown if Mack is the knife, the red creature, or a combination of the two.

Mack is very similar to another one of Smithy's minions, Exor. Both creatures have a large, sword blade-like body facing downwards; both have large eyes near their hilts; and both have strange creatures that serve as a head.

Trivia

 * Mack's name comes from the song, "Mack the Knife" (originally "Die Moritat von Mackie Messer" in German). The song was composed by Kurt Weill, with lyrics by Bertolt Brecht, for the music drama Die Dreigroschenoper, or, in English, The Threepenny Opera. "Mack the Knife" was later covered by both Louis Armstrong and Bobby Darrin.
 * Jack the Knife from Wario: Master of Disguise may also come from that song.