Geoffrey Thibodeux was a small-framed physicist who was granted a bulky body and gravity powers by wristbands provided by the Overmaster, who drafted him into the original Cadre under the alias Black Mass. The Cadre was then sent to battle the Justice League of America. Years later, he briefly lost his wristbands to Wally Tortolino in a card game but had them returned. Eventually, the wristbands and their power bonded permanently with his body. During the Joker’s Last Laugh riots at the Slab, Black Mass used his powers to draw the entire facility into a gravity well. A bullet to the head left Black Mass a vegetable, but he retained his powers and was the cellmate of Doctor Polaris, unwittingly keeping the magnetic villain's powers in check. Still brain damaged, Black Mass was last seen rejoining the Cadre under the leadership of Doctor Polaris in San Francisco. During that time he faced Black Lightning along with Crowbar and Nightfall. He was defeated once again, and sent to jail.
At some point, Black Mass met his demise and has been identified as one of the deceased entombed below the Hall of Justice .
Black Mass has the ability to grow in size and, in doing so, he gains super-strength. He also has some control over gravity.
Black Mass appears in the Justice League Unlimited episode "Clash", with Cadre members Crowbar, Fastball, and Shatterfist; they were defeated by Superman and Batman. Black Mass later returns as a member of Gorilla Grodd's Secret Society..