The Lizard Serum was a serum created by Dr. Curtis Connors that was intended to cause regeneration but instead turned people into lizard creatures.
History[]
The Amazing Spider-Man[]
After receiving Richard Parker's decay rate algorithm, Curt Connors worked with Richard's son Peter to create a regenerative serum, testing it on a three-legged mouse named Fred. Connors came under pressure from Rajit Ratha to create his serum so that it could be used to cure Norman Osborn's terminal illness, but, unknown to Connors, it had the effect of turning Fred into a lizard hybrid due to the lizard DNA used in the formula.
With Ratha planning to secretly test the serum on wounded veterans, Connors injected himself with it instead and mutated into the Lizard. Becoming consumed by the twisted personality of his mutated self, Connors began to spread the serum across the city, turning people into hybrids like himself. Connors then began plotting to use the Ganali Device to spread a cloud of the Lizard Serum from atop Oscorp Tower.
On Peter's orders, Gwen Stacy created an antidote to the Lizard Serum at Oscorp and had her father deliver it to Peter. During a battle atop Oscorp Tower, Peter managed to replace the serum with the antidote, which was then spread across the city instead, curing everyone turned into hybrids, including Connors himself.
Spider-Man: No Way Home[]
After being transported into an alternate universe from before he was cured via the antidote for the Lizard Serum, a variant of Curt Connors still expressed a desire to transform everyone into human-lizard hybrids and resisted Peter Parker's efforts to cure him.
While working on cures for all of the universe-displaced villains, Peter-Three, the Peter Parker from Connors' own universe, confidently stated that he could create the antidote as he had done it before. Using the chemicals in the science lab of Midtown School of Science and Technology, Peter-Three was able to recreate the antidote, modifying it to take on the form of a green gas similar to the gaseous form of the serum itself.
During the final battle at the Statue of Liberty, MJ threw Peter-One the antidote, which Peter-One used to spray Connors, transforming him back into a human once again.