Cletus Kasady was a extremely mentally unstable serial killer who briefly shared a cell with Eddie Brock. When Eddie broke out of prison, a small portion of his symbiote was left behind, which attached itself with Cletus through a small wound on his hand, subsequently mutating in a new red-and-black symbiote, and Carnage was born.

Carnage possesses powers such as shapeshifting and creating weapons from his body. He can also plant ideas in people's heads. Using these abilities, Cletus created a long history of slaughtering people and being put in jail for it.