CARNAGE

Also known as Cletus Kasady, Carnage was born killing. As a child he pushed his grandmother down the stairs, tortured his dog and burnt down his orphanage. After getting put in prison for being oh, a serial killer, his cellmate ends up being a one Eddie Brock (Venom). Brock's Venom symbiote has a baby, since they can produce asexually and all, and bonds with Kasady through a cut. Kasady becomes Carnage, Carnage escapes and then the real fun begins.

The Carnage symbiote ends up being stronger than Spider-Man and Venom combined. He can shape-shift, create weapons like knives and axes with its web substance and plant ideas in people's heads. He can crawl like Spider-Man, regenerate and is immune to infection and disease. This comes in handy since Kasady, without the symbiote, has a form of cancer. He feeds on his victims by just touching them and can see from any part of his body. Carnage even at one point develops immunity to the sonic booms symbiotes usually are vulnerable to. For every murder, Kasady writes "Carnage Rules" on the walls with his own blood. 

Carnage is so powerful that Spider-Man has to make a truce with his arch nemesis Venom just to fight him. Even when Venom re-absorbs his child's symbiote, Kasady just can't stop killing. He paints himself red and goes to town as a regular human murderer. Carnage even has a psychological streak, believing that everybody wants to kill, he just has the guts to do it. He doesn't want money or power, he just likes killing. First introduced in Amazing Spider-Man #344 Carnage was modeled after The Joker to be a darker version of Venom.