Arnold "Lefty" Donovan once served as a hired soldier for HYDRA within the ranks of Daniel Whitehall's faction. Following the Kraken's death during the battle at the Kree ruins, many of Whitehall's grunts were arrested and taken to prison, including Arnold. However, he was soon freed on bail by a representative of Oscorp Industries, who wished to use the soldier as a test subject for a modified Globulin Green serum mixed with traces of Darkforce Energy and some spilled ichor from the demon lords Blackheart and N'astirh. Upon being injected with the combined serum, Arnold gained the physical strength he craved, coupled with superhuman speed and endurance; however, it also horrifically disfigured him and drove him insane, causing him to break out of his containment cell and steal a duplicate Goblin Glider as his means of escape, renaming himself the Demogoblin based on the horrified cries from the Oscorp scientists below him.
Demogoblin was a religious fanatic who had no interest in personal wealth or position. He was determined to destroy all sinners and thus gain redemption for himself. Since his definition of sinner was rather strict and exempted only children, he found himself in continual conflict with Spider-Man, Ghost Rider, Venom and even the original Green Goblin.