Gary Gilbert was the son of an unscrupulous businessman and abusive father, Simon Gilbert. In retaliation, Gilbert and his sister Roxanne became political activists against what they believed were unjust businesses. Gilbert was soon banished from his family home and his sister soon followed of her own volition. Gilbert became increasingly radical and believed only a violent revolution to overthrow the existing American government and capitalist system was necessary. Gilbert used his talents in physics and invention along with training classes offered by Stark Industries to create the weapons and costume of Firebrand. Ironically, he first donned his costume to fight the construction of a community center financed by the Iron Man foundation, which the local black community resisted. Although he clashed with Iron Man, Firebrand's actions helped reveal Councilman Bradshaw's criminal plans behind the community center.
Gilbert retired his costumed identity to become a business agent for other criminals, usually meeting them at an abandoned bar in Medina County, Ohio, known only as the Bar with No Name. As Scourge had already made early successes against low-level criminals such as Gilbert and his clients, Gary called a meeting of criminals to discuss the problem. Seventeen other criminals made the meeting (Water Wizard was late due to a flat tire, which saved his life). All weapons were checked at the door, but Scourge infiltrated the meeting disguised as the bartender. Gilbert and the other 17 were shot down by Scourge, wielding a cut-down .50 submachine gun in each hand.
Firebrand was one of the seventeen Scourge victims resurrected by the Hood in order to try to kill the Punisher, but was killed again by the Punisher shortly afterwards.