Jeffrey Woods, better known as Jeff the Killer or Ominous Unknown Killer is a creepypasta character. He is one of the first famous creepypasta characters to exist.
As a teenager, Jeff and his family moved to somewhere in America. Jeff had no friends at his school and instead, there were bullies. As ambitious bullies do, they insulted Jeff daily, forcing him into a maddening state of depression. Despite this, he willed himself to go to a party at a classmate's house. However, the unnamed bullies were there, and they carried homemade Molotov cocktails with them. Everybody evacuated safely, except for Jeff. He was found horribly disfigured by the flames. Awakening in a hospital with bleached skin and black hair, Jeff finally succumbed to the insanity that is brought with homicide. When he returned to the hospital, he murdered his entire family, all while muttering "Go to sleep.' He carved a scar into his mouth and set fire to the house. Legends, most of which are poorly written fanfictions, say that he is still out there, slaughtering all that he deems worthy of death.
Jeff, in creepypasta lore, is usually paired with a character titled Jane the Killer. Depending on the story, Jane is either an ally/love interest or enemy driven into madness. Another partner that he has in the lore is Homicidal Liu. In some fanfictions, Jeff is a member of The Proxies, an association of creepypasta characters usually depicted being led by Slenderman or The Operator. Thus, through this, he can be associated with Masky and Hoodie, the two proxies shown in the Marblehornets series.