Originally a normal teenager, Jeff’s life turned upside down when a group of bullies attacked him and his brother Liu. Jeff beat up the bullies, but Liu was framed and sent to Juvy, which emotionally scarred him. After this event, Jeff's mother made him go to the birthday party of their neighbor's son, where he confronted the bullies again. In a fit of rage, Jeff killed the bullies, but one of them was able to set him on fire after covering him with bleach and alcohol. Jeff ended with bleached white skin, burnt black hair, red lips and a twisted mental capacity, carving his eyelids so he could never sleep (like normal people at least) and his mouth so he could always have a smile. Jeff then finally snapped and killed his family, even Liu. Jeff is still out there, looking for victims and before he kills them, he tells them this: “Shhh...go to sleep”.
Jeff's weapons of choice are a pair of large kitchen knives, though he usually only uses one so he can use his free hand to cover his victim's mouths and stop them from screaming. It seems Jeff has an abnormally high level of adrenaline in his system, making him able to run faster than a normal person, as well as enhancing his strength. He is also very durable, since he has been shot at by the police and just shrugged them off.
- Knife Throw - Jeff throws one of his knives. This can be done repeatedly despite having only a mere pair of knives.
- Knife Boomerang - Jeff throws a knife at his opponent which comes back to him.
- Knife Dancer - Jeff twirls around with his knives erect, slashing away at the opponent.
- Slash Dash - Jeff holds both his knives and dashes forth doing a slash.
- Throw - Jeff grabs his opponent, lifts a finger to his mouth and whispers, "Shhhh..." before turning them around and impaling them from behind with his knife.
- Reverse Throw - Jeff stabs his opponent in the chest and says, “Hold this.” He then pulls it out and says, “Give me that,” before hitting them with the handle.
- Killer Parry - Jeff's power is a high and low parry. When he lands a hit, he gains a Z. Each Z improves his walking speed and jump arcs.
- Go to Sleep - Jeff grabs the opponent and says, "Shhh...go to sleep." He then carves the opponent's mouth before he slits his/her throat.
- Head Case - Jeff stabs the opponent several times. When he/she drops to his/her knees, he stabs him/her in the throat.
- Jeff bestows sleep wear and a mask before lying down sleeping.
- Jeff puppeteers a policeman's corpse, playing with his mouth and saying, "Watch out, Jeff. This one looks kinda tough!" He then responds with, "Really?" and tosses the body onto the ground while saying, "I think it's time for bed."
- Jeff points his knife at his opponent.
- Jeff laughs and slashes at the screen, causing blood to drip. The words, "Go to sleep," are formed in blood.
- "I hit 'cause I care!"
- "Just die already!"
Jeff was out doing his usual daily routines of murder when he realized something….Jeff was bound to “go to sleep” eventually. He couldn’t let this happen. He wanted to stay around longer and keep doing the thing he love: putting people to sleep. Jeff had then heard of a god that was gathering people to fight and the winner would get their wish granted. Jeff’s wish: immortality.
Slenderman sees Jeff holding a child's head and tries to kill Jeff.
Both are the most well-known Creepypasta characters and they are both pretty much considered to be the Creepypasta mascot.
(Slenderman walks around the forest and sees Jeff the Killer holding a child’s head.)
Jeff the Killer: Ah, making people go to sleep. I love this job.
(Slenderman walks up angrily to him. Jeff notices him.)
Jeff the Killer: Oh! If it ain’t my old pal Slendy! Oh, you wanted to kill this kid? Well, It’s a bit too late for that, but... (Offers him the head.) You can have the head instead.
(Slenderman wraps one of his tentacles around Jeff’s arm and throws him to a tree.)
Slenderman: You killed him... You must die!
(Slenderman tries to launch another tentacle, but Jeff cuts it with one of his knives.)
Jeff the Killer: Come on Slendy, can’t we just talk about this?!
After defeating Mr. Creepypasta, Jeff got his wish and became immortal. Jeff continued his murders until one day the police finally apprehended him. He was sentence to death row to be executed by a gas chamber, but Jeff survived and killed all the remaining officers. He will now spend the rest of eternity doing what he loves….putting people to sleep.
- Jeff's quotes and super move are borrowed from The Joker from Injustice: Gods Among Us.
- Jeff's wish and ending is a reference to the infamous "Jeff is immortal" thing he's sometimes portrayed as.