Jason Voorhees... the ultimate supernatural mama's boy. The story of Jason begins with his mother as Mama Voorhees was the killer in the first movie. It's in the sequel that Jason emerges as the main character and it's the third movie where he gets the infamous hockey mask. There's obviously more to his origins than that and it seems to follow the story of his father and that possibly Mama Voohoos was into Satanism having birthed the son of the Devil himself. Others focus on Camp Crystal Lake itself claiming there's an Indian burial ground involved. Some even joke he's Norman Bates love child with Mama Voorhees, but no one really knows.
No one even knows for sure what he is as some who say he's a zombie can't get around the fact that he's been completely destroyed and returned... he's not a zombie. A more interesting idea is that he's some sort of draugr, a supernatural zombie from Viking mythology. I tend to believe that maybe he's a mix of all of the above and suffering from the ultimate case of road rage although the story general presents that he's not a child killer even if he seems fond of killing teenagers fornicatin' in tha back woods.