Margaret

"I sssense you’re hiding someone under thisss feeble human exterior." -Margaret upon meeting Martha for the first time.

Margaret Connors was married to renowned scientist Dr. Curt Connors and didn’t approve of his risky work with cross-species genetics, one day Margaret found out she had ovarian cancer and was close to dying.

As a last ditch effort to save his wife's life Curt injected her with lizard DNA which saved her, it also resulted in her transforming into a reptilian creature.

Trivia

 * Margaret Connors is loosely based off the Marvel character of the same name.