In early 2010, a mod, named Mythemix, was released for GTA San Andreas that added multiple myths and creatures to the game. Two of these were the Junkyard Killer, found at the Angel Pine Junkyard, and the Headless Man, found at Blueberry Acres. The mod also added a little back-story to the existence of the Killer and the Headless Man.
According to the story, the Junkyard Killer eliminated a college student and sliced his head off. After murdering the student, he was assassinated by a group of unknown people, who most likely were serial killers. Afterwards, they dumped his body in the junkyard next to Mount Chiliad.
His flesh was burned and after a few years his body was somehow reanimated. He has a pump action shotgun and he shoots anyone who gets close to the junkyard. He is wearing a western hat, boots, and a rain coat. All his clothes are black. Players say that the black color is because of his body being burned. He also wears a white mask.
It's hard to find him, as he might be transparent and he might also be seen fighting the Headless Man under Blueberry Bridge.