George Smith was a washed up stunt motorcyclist who was offered $1000.00 by Crime-Wave to kill Daredevil. After fighting Daredevil he reformed and turned to the side of good. Some months later, he teamed-up with the Ghost Rider and also aided the Avengers against the Grim Reaper. Nothing was heard from him in a long time until he was recruited for the 50 States Initiative and became leader of the Georgia based Initiative team, The Cavalry. After the Secret Invasion, the 50 States Initiative was put on hold. The Cavalry team however stayed together and kept fighting the good fight.
During the events of Fear Itself, Stunt-Master was seen trying to keep a panicking crowd in tome with his former Initiative team-member Thor-Girl. He was however overwhelmed by the croud and seemed to lose the battle.
Though he possesses no super-human abilities Stuntmaster is a skilled Stuntman and motorcyclist. He also built himself a motorcycle which could fly through the air.