As a young man, Dennis Dunphy idolized costumed super heroes, especially Captain America and Daredevil. Dunphy was a successful college football player and tried to go professional before realizing that his skills weren’t sufficient after he wasn’t picked up by any of the teams he tried out for. He stayed in good shape and hoped for his big break until a man at the gym told him about the Power Broker (Curtiss Jackson), a mysterious businessman who could grant Dunphy superhuman strength for a price. Dunphy underwent the augmentation process, increasing his bulk and endurance, and the Power Broker said he would need regular stabilization pills to remain healthy; Dunphy did not learn until later that fifty percent of the augmentees became monstrous, mindless brutes, and he was unaware that the “stabilization pills” were addictive drugs designed to ensure the loyalty of the Broker’s clients. Now far too strong to play football against normal men (whom he could easily kill by accident),Dunphy returned to Power Broker for advice on potential careers. They directed him to seek a career with the Unlimited Class Wrestling Federation (UCWF), which pitted super-strong wrestlers against each other for public entertainment. Sporting a Mohawk and calling himself Demolition Dunphy, Dennis was chosen to face the Fantastic Four’s Thing (Ben Grimm) in the first public UCWF match during a period when the Thing had disassociated with the Fantastic Four; however, UCWF founder Ed Garner tried to pay Dunphy to throw the match, fearing audiences would hate to see the celebrated Thing lose. Dennis refused the bribe and helped Thing persuade Garner to keep the new league legitimate, but the Thing won the match anyway.
Dunphy met Captain America (Steve Rogers), who was investigating the Power Broker and one of his suspected clients, the Super-Patriot (John Walker, later USAgent/Jack Daniels). Seeing an opportunity to become a super hero, and seeking vengeance on the Broker for turning himself and his wrestling colleagues into addicts, Dunphy canceled his professional commitments, shaved his head and donned the outfit patterned after Daredevil’s. Calling himself Demolition Man (or D-Man for short, playing on the word “demon”), Dunphy helped Cap find Karl Malus, one of the scientists responsible for the Broker’s augmentations. Dunphy soon proved himself by rescuing Cap from a deathtrap arranged by Malus; however, Dunphy was soon after captured by several augmentees, and then further augmented by Malus, straining his mind and body. When Cap rescued him, a crazed Dunphy attacked the hero before succumbing to a heart attack; though Malus reversed the process, Dunphy was briefly hospitalized and he has had recurring heart problems thereafter.
More recently, Dunphy became progressively more delusional and believed he had a divine mission to gather various gems (which he apparently believed to be the powerful Infinity Gems), stealing jewels from the scenes of robberies he had thwarted. Reporter Ben Urich and Dunphy’s boyhood idol Daredevil (Matt Murdock) convinced D-Man to leave the sewers and seek professional help, and Dunphy was arrested for vagrancy. Despite his legal troubles, Dunphy was considered a potential recruit by the U.S. government’s Initiative program after the passage of the federal Superhuman Registration Act.
Dunphy has superhuman strength (lifting up to 15 tons), endurance, and durability. He has a history of cardiac problems linked to severe physical exertion. He survived for months encased in ice, though it left him slightly brain-damaged and sometimes delusional. An expert wrestler trained in unarmed combat by Captain America, Dunphy can pilot Avengers Quinjets and is a capable motorcyclist.