Jason Voorhees is the main antagonist and villain protagonist of the 1981 slasher horror film, Friday the 13th Part 2, and the rest of the Friday the 13th movies and its two remakes (except from Part 5: A New Beginning). He is a hockey-masked, immortal, zombified, undead serial killer. He is nominated in AFI's 100 Years... 100 Heroes and Villains and Wizard Magazine rated him the 26th greatest villain of all time.
He was somehow able to return, however, though it is not explained how. The FBI finally aware of his existence and set up a sting operation and successfully managed to shoot him down and then they blew him to pieces. However, not even this could kill him by now. His heart lived on, and at the morgue, it hypnotized a coroner into eating it. Jason's spirit along with the souls of his past victims possessed the coroner.
In the form of a worm-like creature, Jason's soul transferred to different people to possess them (gruesomely melting and killing his previous host once he leaves them), and killed several people in an attempt to be reborn through Diana Kimble, her daughter Jessica, or her baby daughter Stephanie, because, as the only remaining blood relatives of Jason, they are the only ones he can be reborn through. Likewise, only Diana or Jessica can truly destroy him by striking at his heart with a mystic dagger. Bounty Hunter Creighton Duke told all this to the film's male protagonist, Steven (Jessica's boyfriend) and Steven told Jessica everything Steven was told by Duke. Jason managed to kill Diana, and eventually he managed to discover her corpse at the Voorhees houseand was reborn through it.