Dr. Curt Connors lost his arm in a explosion when he was helping American soldiers. Connors pursued genetic research that would allow lost limbs and organs to regenerate using Lizard D.N.A. However, with no one else to test his serum, Connors experimented on himself, successfully growing a new arm. But the experiment further mutated Connors, transforming him into a human-lizard hybrid with a reptilian mind bent on world domination calling itself the Lizard. Spider-Man has confronted the Lizard numerous times and managed to use the research left behind by Dr. Connors to transform him back into his human form each time. The latest formula did not completely succeed, leaving Connors mind in the Lizard's body. Good news is, he's at least on our side.
Current Incarnation:
The Lizard (Classic)
Former Incarnation:
The Lizard (Villain)