Doctor Curtis Connors was a notable genetic biologist on payroll from Oscorp Industries who was assigned with Richard Parker to work on combining desirable physical attributes of animals with humans to improve health, including restoring his own amputated right arm, which had been lost years prior in a terrible accident and now has replaced it with a fully functioning, mechanical prosthetic arm. Obsessed with completing his goal no matter the cost, Connors created a serum made from modified lizard DNA that had been electrolyted and injected it into himself, hoping to regrow his arm somehow. Needless to say, the serum worked all too well, mutating him into a feral Cross-Species brute known as the Lizard. Spider Man, the secret identity of Richard's son Peter, was able to take the creature down, and brought him into S.H.I.E.L.D. custody, but Connors was eventually broken out by some of Oscorp's more elusive operatives and forcibly recruited into the corporation's superhuman initiative in order to counteract S.H.I.E.L.D.'s Avenger Initiative.