There is no profession better than a Murderer..

Jeff has extremely pale skin and burnt eyelids, which gives him a more ghostly appearance. Later, Jeff acquired his most distinctive feature, the Glasgow smile, which he carved into his face with a knife. His physique is usually described as slender, but at the same time toned and reaching a height of about 5-6 feet (1.5-1.8 m). His clothes usually consist of a pair of black skinny jeans and a white hoodie, sometimes stained with the fresh and old blood of his victims.

Human Conditioning: Despite the fact that Jeff is a dangerously strong and bloodthirsty killer, who under no circumstances should be underestimated, there still remains the fact that Jeff's body is only above the average human and has its limits. There are times when he can still be overpowered, outnumbered and outsmarted. Similarly, although Jeff is at the peak of human development, with physical prowess far beyond the average citizen, over time Jeff will still grow old and one day lose his physical prime, despite the fact that his life expectancy is also at the peak of the human level. In conclusion, Jeff can only resist common diseases up to the peak human level, which means that he is not completely immune to diseases due to the fact that he is still human. However, considering all this, Jeff's level of qualities may not allow him to endure much. He can't stand things like beheadings, powerful explosions, etc. Because his condition under neurological anesthesia only suppresses pain, he is not invulnerable or immortal, and he is incredibly difficult to kill.
Cutting certain vital parts of his body can disable him, depending on the severity, and although his tolerance for blood loss turned out to be high (for example, he was brutally impaled on a tree branch by a Slender Man before he came to his senses and killed a married couple who found him lying on the ground after a fight) It still has its limits.

Insanity: Although he has his clever and manipulative moments, it should be noted that Jeff is still insane due to the depression of the central nervous system due to neurological damage from anesthesia caused by arson with a naturally produced chemical called “ethyl chloride” (an anesthetic chemical derived from bleach reacting with with water and ethanol contained in vodka) poured on him (especially on his head). Because of this, he most likely suffers from inhibition of nerve impulses responsible for sensory neurons, very similar to the symptoms of numbness in frostbite.
Due to his insanity, he no longer controls his bloodlust, and it will manifest whenever it happens, as it does not affect his propensity to kill. When he was set on fire, doused with bleach and vodka, it slowed down his sensory neurons of the central nervous system, which reduced his ability to concentrate on certain things. When the thirst for blood manifests itself in him, it sometimes becomes irresistible to the point that he is unable to think. He tends to make unpredictable moves and decisions. Sometimes Jeff goes straight for the kill, instead of acting pragmatically and making plans.

Jane is a murderer
Obviously, Jane the Killer was based on Jeff the Killer. It is believed that Jeff killed Jane's parents, eventually causing Jane to go crazy, and encouraged her to become a female version of Jeff and carry out her revenge, which is to hunt down and kill Jeff. Others believe that Jeff managed to kill her and his entire family, and that he set Jane on fire, as a result of which she was disfigured. Although these are all assumptions.

Slenderman
Some theories suggest that Slenderman and Jeff the Killer are aware of each other's existence. First of all, it is assumed that they are rivals of each other. To defeat each other, Jeff uses his knives, and Slenderman uses his tentacles.

Jeff looks like an extremely violent, sadistic and insane man. The smile on Jeff's face reflects his sadism and general bloodlust. His appearance shows how much he is focused on hurting someone.

In many fun images, Jeff is primarily presented as a vain, narcissistic emo type teenager who absolutely does not intend to follow the general rules and listens only to himself. He seems to be a master of his craft when it comes to his emotions, managing to hide them and constantly demonstrating ignorance towards everything.

It is believed that Jeff is vain and self-satisfied, but the reality is that Jeff actually makes himself and experiences numerous stresses about his appearance. Jeff also seems to have problems with people leaving and completely forgetting him in their lives. Before he went crazy, he was very quiet and antisocial, and people didn't know much about Jeff. His voice also seems very creepy and soft, and he speaks in a rather calm and polite manner.

Jeff started out as an ordinary teenager from the suburbs, living with his mother Margaret, father Peter and brother Lew.

At some point in Jeff's life, when he turned 13, he and his family moved to a new neighborhood after his father got a promotion. Jeff and his brother were excited about the idea. Shortly after Jeff moved into the neighborhood, he had a strange feeling, but he didn't pay much attention to it.

A day later, Jeff and Lew went to a bus stop where there were no people. While they were waiting for the school bus, three children, Randy, Troy and Keith, approached the brothers and attacked them, threatening them with a knife, while taking Lew's wallet. That's when it occurred to Jeff again, and he got into a fight with three bullies, disabling all three of them, shocking Lew. Jeff and Lew left the scene after the school bus pulled up and went to school, believing that they were above suspicion.

However, the next morning, the police arrived at Jeff's house, and Jeff and Lew were accused of attacking the trio without apparent motivation, even after Jeff tried to tell the police that they were attacked, the police did not believe him. Jeff rightfully took the blame for all this on himself, and the police were going to send him to a correctional institution for a whole year, but Lew intervened with a knife in his hand and took the blame for the whole incident on himself, showing cuts and bruises on his arm as proof. Then Lew was taken away instead of Jeff, leaving Jeff depressed.

Two days later, Jeff became more and more tormented by feelings of guilt and loneliness. However, on Saturday morning, Jeff's mother insisted that he go to a neighbor's birthday party, believing that it would make him happy. Jeff reluctantly went to the party, which soon distracted him from thinking about Lew and made him feel a little better. However, the situation took a turn for the worse when Randy, Troy and Keith tracked Jeff down at a party and confronted him with anger in their eyes, showing that they clearly wanted a fight. Jeff tried to reason with Randy, believing that the odds were even between them, since he managed to defeat them before they sent his brother to a juvenile detention center. Randy rejected it and said: "I don't strive for equality, I strive for victory."

Randy then brutally attacked Jeff, while Troy and Keith held parents and children at gunpoint to prevent them from stopping the fight. During the fight, Randy smashed a bottle of vodka over Jeff's head, dousing him with alcohol. After Randy incapacitated Jeff, he constantly yelled at Jeff, demanding to fight back. After Jeff tried to stand up, Randy finally insulted Jeff, telling him that Lew would rot in prison and that he should be ashamed of himself for not doing anything about it.

This infuriated Jeff, who got up and knocked Randy to the ground. He struck Randy hard in the chest, which caused Randy's heart arrhythmia, which led to his death. Troy and Keith, enraged by Randy's death, started shooting at Jeff with their pistols, but they failed to hit him. After the two ran out of ammunition, Jeff lured them into the bathroom, where he fatally wounded them.

During the fight with the Whale, a bath of bleach was poured on Jeff, and the Whale took this opportunity to set Jeff on fire by throwing a lighter at him. Due to the fact that Jeff was soaked in alcohol and bleach, he ignited, making it almost impossible for him to extinguish the flames on his own, then Jeff fell down the stairs of the house and lost consciousness when the flames engulfed him.

Jeff woke up in a hospital room with bandages covering his face and body, and his mother informed him that Lew was being released from prison after witnesses accidentally overheard Randy mention that he was responsible for getting him into prison. A few weeks later, Jeff's bandages were removed, revealing a deformed face. Jeff liked his new face, and when his family noticed his behavior, doctors mistakenly assured them that it was the result of taking painkillers.

After Jeff's mother was taken home that day, she woke up to find Jeff in the bathroom, burning out his eyelids and carving a Glasgow smile on his cheeks. She realized that Jeff had gone crazy, and she knew that he needed to be killed. While reporting this to Jeff's father, Jeff overheard it and proceeded to kill his parents. Liu was woken up by the noise and tried to avoid it by trying to fall asleep again, however, Jeff sneaked into the room and told Liu, "Go to sleep," before stabbing him in the chest. Lew's fate remained uncertain.

Jeff then began committing serial murders, killing those who refused to sleep at night, Jeff became infamous as the "Sinister Unknown Killer".

Despite the fact that Jeff is human, he seems to possess incredibly powerful abilities that apply only to his human qualities, such as incredible stealth, superhuman speed and brute force, which he uses to ruthlessly kill his victims, being able to defeat his parents and brother by simply gutting them.

After exposure to bleach and alcohol on the skin, Jeff's nervous system slowed down due to a decrease in electrical signals in his nervous system, which increased his pain tolerance. A few things that make him stronger are his intense hatred and bloodlust, as well as his tremendous stamina. In recent years, Jeff has been portrayed as a charming man who manipulates people into trusting him only to stab them in the back later.

Unlike other serial killers, Jeff's thirst for murder is unusually insatiable. This is because these urges were triggered by the feeling of sadistic pleasure he took in causing as much pain to others as possible. His predilection for murder has led to his gaining notoriety, his absolute willingness to show such disturbing cruelty allows him to cause fear in others. Because of the boundless extent of his sadism, Jeff can easily break the will of others. He has also demonstrated that he emits a murderous aura to intimidate others, which they perceive with their inner instincts. This can be used to discourage them from obeying/running away, leave them frozen in fear, and even cause them to have painful hallucinations to such an extent that their mind will be forced to believe that they are real. One example is his menacing presence, causing such fear that the victim has a tactile hallucination in the form of the dead body of a young girl, which they found in their closet, despite the fact that the police do not have any personal information about her. Jeff also has extensive knowledge of murder, which allows him to sense the weaknesses of even his strongest victims and use them to inflict significant harm on them, if not kill them.

Jeff really lives up to his name. He is a wild maniac, looking for trouble, chaos and murder wherever he goes, and taking as many people as possible to a depth of 6 feet underground, constantly avoiding the authorities.

His intentions go much deeper than just killing his victims. His bloodlust first manifested in his mind as the unbridled pleasure of hurting others. If it wasn't for this sadistic nature, Jeff would never have resorted to murder at all. Because of this, he sometimes takes his time with his victims, subjecting them to outrageously cruel tortures while they are still alive.

This sadistic nature has led him to the ability to exploit the weaknesses of others, whether human or supernatural, which makes it easy for him to figure out how to at least hurt most living beings. It is also possible that Jeff's psychopathy will eventually overtake him and begin to suppress him, eventually leading him to suicide, which will give him 8 points in terms of danger level.