Jack was a bad child who disobeyed his parents and hurt animals. One Halloween, he came to the house of the Crime-Master, who knocked him out with gas and kidnapped him. Initially, he was afraid of him, but he soon grew to consider him his true father. Over time, he was trained to be a master assassin, and to prove his allegiance to him, Jack returned to his parents and murdered them with no remorse nor mercy. After the fact, he developed his signature, in which he scooped out the brains of his victims and placed a candle inside them, giving them the appearance of a jack-o-lantern. Jack took the name Jack O'Lantern and killed those who had used the name in the past In the Eastern European country of Nrosvekistan, Crime-Master sent Jack to find Doctor Ekmecic, a specialist in making weapons from Antarctic Vibranium. The new government agent Venom, war hero Flash Thompson, was also trying to bring in Ekmecic, and though neither succeeded, they became arch-enemies
Later on, while Venom was on a mission in the Savage Land to confiscate Crime-Master's Antarctic Vibranium shipment, he learned Venom's identity and sent Jack to kidnap Betty Brant, his girlfriend, forcing Venom to hand over the Vibranium to Crime-Master to ensure her safety
After Flash's father died, Jack appeared at his funeral and dragged Flash to Crime-Master's headquarters, where he threatens to kill Flash's family if he doesn't go on a mission for him in Las Vegas with Jack O'Lantern Together, they broke into a secret lab hidden within a Vegas casino with the intention of stealing the Toxin symbiote. But the Venom symbiote reacted to it negatively and tried to destroy it, leading to an all-out brawl between an out of control Venom and Jack O'Lantern. Jack was no match and promised to leave his family alone if he let him leave with the symbiote. Venom regained his composure, but Jack fled with Toxin
