is the titular villain of the creepypasta story of the same name. He was originally a young latent psychopath who brutally beat up a trio bullies, Randy, Keith and Troy, who were picking on him and his brother Liu in the town they had just moved to. Liu took the blame for it and was arrested, sending Jeff into a depression. Later, the bullies attacked Jeff again at a party, and Jeff killed all three of them, but not before getting covered in bleach and lit on fire by Keith as he died. During this fight, Jeff's mind permanently snapped.
When Jeff woke up, he was in a full body cast at the hospital. When the bandages were taken off, it was revealed that his face had become disfigured and ghastly pale from the burns, with bright red lips and a leathery texture. Jeff said that he liked his face this way and laughed hysterically, but the doctor foolishly thought that this insanity was just the result of the painkillers and let Jeff and his family (including Liu, who was released) go home.
Later that night, Jeff's mother found that he had carved his face into a permanent smile so that he would no longer have to exert energy to smile, as he put it, and burned off his eyelids so that he could always see his face. Jeff's mother went to her husband to tell him that their son had gone completely mad and needed to be killed, but Jeff caught them and knifed them to death. This woke up Liu, who confronted his brother but was killed as well, with Jeff telling him as he was about to plunge the knife into his body, "just go to sleep".
Sometime later, an "ominous unknown killer" emerged and went on a killing spree. A boy who was lucky enough to survive the killer's attacks described the man as having inhumanly pale skin, a hideous smile, and dark, ominous, constantly open eyes. When he tried to kill the boy, he told him to "go to sleep".
He is known to be hunted by Jane the Killer, who kills Jeff's planned victims before he has the chance to.
Against Sora's TeamEdit
Fanboy, Chum Chum, Yakko, Wakko, and Dot entered the forbidden world when they were told not to, and like the Kreamy Cold, and Big Yellow, Jeff is lose roaming other worlds. Jeff later almost killed Sora when both of them were face to face, but were both attacked by Slenderman who was also roamed free to other worlds. After the battle, Jeff escaped but was defeated by Moka Akashiya (Inner) with one kick and Lock, Shock, and Barrel trapped him in a cage. Jane the Killer showed and thanks the team for capturing him and letting her finish the job, and Jane becomes allies with them and Jane finally gets her revenge.