Lizzie was an American crocodile living in Everglades National Park, where she ate one of the canisters containing Energyne's "Project Rampage" pathogen after it fell to Earth following the explosion of the Athena-1 satellite. The pathogen modified Lizzie's genome, drastically increasing her size, strength, and aggression, while also causing her to develop the physical characteristics of other species. In a short span of time, Lizzie went from a normal crocodile to a giant monster.