Nack the Weasel, is a purple wolf-weasel hybrid that first appeared in the Game Gear video game Sonic the Hedgehog: Triple Trouble. His character is a treasure hunter in search of the Chaos Emeralds; however he does not know of their true power and merely wants to sell them for profit. He is a slick, sneaky, and mischievous character who will steal the Emeralds for an easier job.

Nack the Weasel also appeared in Sonic Drift 2 as a playable racer, and in Sonic the Fighters as a playable fighter. He was set to appear in Sonic X-treme as a boss character, but the game was canceled. Nack makes a cameo in Sonic Generations on a "Wanted" poster in the City Escape stage. The poster reads "Wanted Fang A.K.A Nack"