Curtis Connors (Earth-1600)

Dr. Curtis Connors (a.k.a. the Lizard) is a biologist and a former scientist of Oscorp Industries. He lost his arm due to an explosion while conducting an experiment at Oscorp and lost his job afterwards. He devoted himself into making a serum that could regrow missing limbs based on reptillian DNA, but secretly to regrow his own arm. This transforms him into a giant, humanoid lizard. He's not only Spider-Man's first supervillain, but he has proven to be a threat to national security by S.H.I.E.L.D.