Former lab assistant to Spencer Smythe, Mark Raxton helped to develop an experimental metallic alloy obtained from a meteor containing organic matter. During an argument between the two, the metallic alloy spilled over Raxton’s body and was absorbed into his skin. Fearing for his life, he ran for the nearest hospital, only to discover that the alloy had granted him extraordinary powers. Realizing the potential his new abilities gave him, Raxton, now calling himself the Molten Man turned to crime to further his gains. Peter Parker, as Spider-Man, was forced to nearly miss his high-school graduation to stop the Molten Man's first crime spree.
After graduating high school, Elizabeth Allan worked as a nurse to aid Raxton, her step-brother. It was only after Molten Man made an attempt to attack her, he realized that his step-sister was the only member of his family who had not abandoned him. After desperate attempts to cure himself involving criminal activities, Raxton ended up in the Vault, the superhuman prison in the Colorado Rockies.
Years later, reconciling with Raxton, Liz and her husband Harry Osborn gave Raxton a job as head of security at Osborn Industries. Raxton supported Liz when Harry went back his villainous ways and later helped Spider-Man to capture him. Molten Man and Spider-Man have since become friends, but when Ben Reilly assumed the role of Spider-Man they have minor disagreement until they allied themselves against Gaunt.
Raxton also crossed paths with Daredevil when he was affected by a gas made by Mister Fear. Daredevil managed to dispose the gas before he managed to hurt anyone and revealed that Raxton was betrayed by one of his own people.
Some time after that, Molten Man was abducted by Norman Osborn, the original Green Goblin, and was brainwashed. Under mind control, Molten Man attacked and killed Osborn's henchwoman Alison Mongrain, who happened to be one of the few people who knew the true cause Mary Jane's miscarriage. While Molten Man has since recovered from the mind control, he still bears a heavy burden of guilt over the incident.
Sometime after Civil War|Superhero Registration Act came a law and Spider-Man had publicly revealed his identity. Chameleon recruited Scarecrow, Will-O'-The-Wisp, Electro and Swarm to the group he himself called Exterminators. He then blackmailed Raxton to join the group by threatening to hurt a child who he was mentoring. They made Liz call Spider-Man to come her apartment by threatening to hurt Normie. When Spider-Man arrived with Black Cat they were attacked by Raxton, Will-O'-The-Wisp and Scarecrow. Spider-Man and Black Cat managed to beat them and Spider-Man made Raxton tell them where Chameleon was. He told that Chameleon was after Aunt May. Raxton apparently was arrested shortly after Spider-Man and Black Cat left to rescue Aunt May.