Lizard

First Appearance and Origin - Amazing Spider-Man #6

by Steve Ditko, 1964

When reports of a human lizard in the Florida Everglade spread, the Daily Bugle challenges Spider-Man to defeat the Lizard. Spider-Man drops by Jonah's office to harass the publisher and accept the Daily Bugle's offer. Jonah summons Peter Parker in order to accompany him to Florida to snap photos of the Lizard and Spider-Man.

In Florida, Peter sneaks off to change into Spider-Man while Jonah checks into the hotel. When he enters the Everglades to investigate recently Lizard sightings, Spider-Man is ambushed by the Lizard. A short battle ensues which ends with the Lizard flinging Spider-Man through the Everglades.

Spider-Man stops by the home of one Dr. Curt Connors, local reptile expert. Once there, he speaks to Dr. Connors' wife. She explains that her husband was investigating the regenerative abilities of reptiles. After extracting a serum from experimental lizards, he drank the serum himself in an attempt to regenerate his lost arm. Instead of simply regenerating his arm, the serum mutated him into a the giant humanoid lizard that was terrorizing the Everglades.

Using Dr. Connors notes and his scientific know-how, Spider-Man developed a counter-serum. Searching the Everglades, Spider-Man finds the Lizard planning to destroy humanity with a reptile army. During the fight, Spider-Man manages to force feed his counter-serum to the Lizard forcing him to transform back in Dr. Curt Connors.