Carl Scraton was the psychotic brother of Gordy Scraton, and the enforcer of the Scraton gang in the 1950s. He was also a Toy, transformed into a loyal brother by Gordy's need.
When Carl was sent to kill Dennis, the Toy that had become Mikey's brother, Mikey killed Carl to stop him. Once dead, Carl's true nature was revealed. (PROSE: Bad Therapy)