Personality: Sam Guthrie is Kentucky born and bred, the son of a coal miner and, oh so briefly, a coal miner himself. Sam is the essence of duty to family and friends, moral wholesomeness, and, in truth, a charming naivete'. He trusts first, he makes friends by default, and while he is occasionally cautious in unknown situations, he always responds with a cool head.

Durability:Normal; when using his superhuman powers, however, Cannonball achieves metahuman durability due to an energy field which forms over his body.

Strength: Cannonball possesses the normal human strength of a young man of his age, height, and build. However, when he uses his powers to apply thrust beneath him, the force thus generated enables him to bear aloft over a ton of weight in addition to his own

Known superhuman powers: Cannonball possesses the ability to bodily generate thermo-chemical energy and release it from his skin. This energy, released by an act of will, is accompanied by smoke, flame and condensation, much like the exhaust of a rocket engine. At his present level of experience, he can only release this energy in one direction, beneath him. The equal and opposite reaction to this thrust causes his body to be propelled through the air like a human rocket.

At first, he could not stop his propulsion until his immediate store of energy was depleted or until he hit an obstruction of sufficient mass to stop him. However, he has since learned how to cut off his propulsive power at will. As a side effect of forming the thermo-chemical energies over the surface of his body, Cannonball becomes virtually invulnerable. Accompanying the release of energy is a half-inch thick energy field which channels the explosion and protects his skin from the direct effects of the blast. It also negates momentum and related energy effects thereby cushioning his entire body from any impact up to a half-minute from the depletion of his energy. Not only is he protected from rough landings, but he is also protected from nearly all types of injury while in flight. The protective field also protects any person or object with which he is in physical contact.

Working in the Kentucky coal mines, Sam's father inhaled too much coal dust and eventually died. Sam was an intelligent young man, an avid reader (especially of science fiction) who had gained a college scholarship. However, with the death of his father, the sixteen year old boy felt that it fell to him to support the family and so Sam got a job working in the coal mines as well. One day, the mine collapsed on the workers and Sam manifested his mutant blasting powers in order to save himself and his partner.

Donald Pierce, a renegade member of the Inner Circle of the Hellfire Club, located Guthrie and learned of his superhuman powers by means of a machine the Hellfire Club had built by adapting plans they had stolen from Professor Xavier's Cerebro device. Pierce recruited Guthrie to be one of his operatives, and sent him into battle against Xavier and his X-Men. However, during the battle, he refused to obey Pierce's orders and Pierce attempted to kill Guthrie in retaliation. Xavier, however, saved Guthrie's life by defeating Pierce. Realizing that Guthrie was not an evil person, Xavier invited him to join the Institute as part of the Reserve Team. Sam has also elected to carry on with his education.