Laughing Jack is the titular antagonist of the creepypasta story of the same name and its prequel, "The Origin of Laughing Jack".
Laughing Jack was created by a guardian angel as a lonely child that abused by his mother. Laughing Jack's colorful appearance turned monochrome and he became emotionless as a result of his imprisonment.
Jack became more evil as Isaac became a serial killer who would commit his murders in front of Laughing Jack's prison. Isaac rediscovered the box Jack was trapped in and accidently released him. Resentful of his former friend and having a newfound love for violence, Jack brutally murdered Isaac and continued spreading his own brand of "fun" to all the other children of the world.