Jason Voorhees is the main fictional character from the Friday the 13th series of slasher films. A vicious serial killer and mass murderer, he has a presence in all of the films, even when he is not the killer. With his trademark hockey goalie mask and machete, he is arguably among the most recognizable villains from any slasher film. Throughout the series, Jason has never spoken aside from when he drowned as a child, and from occasional mumbles, grunts, and groans, and a few words in the eighth and ninth film of the series, the latter when he possessed another man's body. Jason is credited as having been created by Victor Miller, the screenwriter of the first Friday the 13th film, in spite of the fact that he barely appeared in that film and much controversy exists about his creation, with Ron Kurz and Tom Savini both arguing they deserve some of the credit. For his part, Miller has gone on record as saying he has avoided watching the sequel films and that he has great reservations about how Jason has been handled.
Childhood and drowning
Little about Jason's life prior to his drowning at Camp Crystal Lake has been explored in the films. It is established that he was born June 13, 1946 to Pamela Voorhees. Most other details have been left untouched by the film series, the gaps filled in by the novelizations of the early films (particularly for Part 2). The canonical nature of these novels are unclear, but a few details have been incorporated into later films, such as Elias Voorhees being the name of Jason's father. Outside of the Jason Lives novelization, Elias has not been depicted in any media; his ties to Jason's back-story are left unclear in the series, although he was mentioned by name in Jason Goes to Hell: The Final Friday.
Jason's mental abilities and possible retardation have not been officially addressed, and have been depicted with conflicting evidence by both the films and outside sources. Jason's deformed look and hydrocephalic features are also unclear when taking other sources into consideration. The novelizations are explicit that Jason was born physically normal, having developed the deformation seen onscreen through a "regeneration ability" that manifested itself when he had been at the bottom of Crystal Lake. Adding to this is that Victor Miller has stated that Jason was originally conceived of as a normal child akin to the novelizations.
However a flash back of Jason drowning in the original film clearly shows a deformed head; this combined with his mother saying "Jason should have been watched, every minute, every second. He was-" and then pausing to add "he wasn't a very good swimmer" hints that Jason's mother was about to admit that Jason was retarded or her son before catching herself and correcting herself. It was Tom Savini who designed the deformed look seen in the film. Supporting this scenerio is the fact that in Jason Takes Manhattan Jason's visage appears frequently to one of the main characters, his appearance growing from normal to deformed with each appearance. Later films, specifically Jason X, have taken the concept of Jason possessing a regenerative ability. Despite this, there has yet to be anything surrounding Jason's drowning directly addressed in the film series. The closest thing that refutes the novels' explanation is in Freddy vs. Jason, the more recent of the films, in which a dream sequence from Jason's own mind depicts him as a young child at the camp with his characteristic deformities. However, the canonical importance of this perspective is left to debate.
The only established facts retained through the films' continuity are that Jason supposedly drowned at Camp Crystal Lake in 1957, his body never found. This incident drives his mother to take revenge on those she feels were responsible. After the camp is closed due to the murder of two counselors she had killed, Mrs. Voorhees goes to great lengths to keep the camp from reopening. Her final attempt is a killing spree that ends with her own decapitation in the sole survivor's act of self-defense. It has also been said that the camp counselors were, instead of saving Jason from drowning, having sex, therefore causing Jason's mother to kill them. Although it was not explained that if Jason did survive the drowning and managed to become a full grown man (albeit with a warped mind), why he did not try and seek out his mother to inform her of his survival remains unexplained. Apparently, however, just as Pamela felt she needed to seek revenge for Jason's apparent death, Jason felt the need for revenge when he witnessed his mother's death from afar.
Based on the information given in the films, it's presumed that Jason acts out his first murder on Alice Hardy, the woman responsible for his mother's death just two months earlier. It's further suggested that soon after he retreats to the deserted grounds of Camp Crystal Lake and makes his home in a crudely built shack with his mother's severed head in his possession. It is not until five years later does Jason begin a seemingly unstoppable killing spree when two counselors in the adjacent training center sneak onto the closed off area. This event triggers Jason to leave the grounds to kill over thirty victims during the course of a few days as depicted in the second, third, and fourth films in the series. During his spree there are attempts to stop Jason by the few survivors, but none are entirely successful until a young Tommy Jarvis drives a machete deep into his skull and then repeatedly strikes him again and again. This evidently ends Jason's reign of terror, but the cost is Tommy's own mental health and he spends several years in various psychiatric hospitals. It is during this time that Jason has been buried. According to the Jason Lives novelization and screenplay, Jason's father intervened to keep his son from being cremated by paying for a proper burial.
Return from the grave
As made clear in A New Beginning, in which copycat killer Roy Burns assumes Jason's identity to exact revenge for the death of his son, Tommy Jarvis is still haunted years later by his encounter with Jason. Jason Lives begins with Tommy taking a friend to help him dig up and cremate Jason to make sure that he will not return. However, seeing Jason again stirs memories and Tommy, mirroring his mad attack at the climax of The Final Chapter, stabs the rotting corpse repeatedly with a metal rod. Soon the rod attracts lightning and the burst of electricity brings Jason back to life in a fashion modeled after Frankenstein. With a stronger and more invulnerable Jason roaming back to the Crystal Lake (renamed Forest Green as part of the town's efforts to distance itself from Crystal Lake's violent history), Tommy devises a plan. Luring him onto the middle of the lake, returning Jason to where he drowned, and chains him to the bottom of the lake. Tommy assumes Jason is "home" and is never seen in any of the subsequent films.
When The New Blood begins Jason's body remains chained in lake's waters some years later after the events of the previous film. His dormant body is resurrected again via the psychokinesis ability of a young woman who had accidentally killed her father with the same powers in the same lake. After using these powers once again she somehow uses her abilities to revive her father, who leaps out of the lake and pulls Jason back into the lake. Jason is brought back again at unspecified time later in the eighth film, Jason Takes Manhattan. Brought to life once more with electricity, he boards a cruise ship named Lazarus and kills several high school graduates on their way to New York, and continues to hunt the few survivors of the sunken ship onto the city's streets. In the climax of the film, Jason is caught up in a flood of toxic waste that is pumped in Manhattan's sewer system. The fate of Jason in this event remains debated as the only evidence of him when the waste clears is a young Jason, free of any deformities. As the film depicts one of the characters seeing flashes of Jason, it is possible that this is a mere psychic illusion and not a physical representation of Jason. The confusion of this ending is furthered by Jason Goes To Hell which begins with Jason already alive, never explaining how he escaped the waste in New York.
To Hell and clash with Freddy Krueger
Regardless of how he had survived and made his way back to Crystal Lake, the ninth film opens with Jason caught in the sights of the FBI. He is overpowered and quickly blown apart. It is established in the film that though Jason's body has been destroyed, his spirit lies in his untouched heart. It is this physical manifestation of his soul that passes from host-to-host in a quest to find another Voorhees, the only means by which he can be reincarnated into his familiar form; but a Voorhees also possesses the only power to destroy him. Once reborn through his sister's body, his niece takes up a special dagger empowered by her bloodline, and uses it against Jason, sending him to Hell. Afterwards his mask is on the ground when a clawed glove bursts out from the ground and drags it down.
When Freddy vs. Jason begins Jason is living out previous murders while in Hell. During this he is provoked by his mother to "wake up", which results in a physical resurrection. However, it turns out that Jason was brought back not by his mother, but by Freddy Krueger, the supernatural serial killer of the A Nightmare on Elm Street films who can manipulate dreams. Freddy's objective is to use Jason as a mere tool to kill the children of Springwood so they will be attributed to Krueger and thus produce enough fear to restore his powers. However, Jason turns out to be too much for Freddy to control and Freddy resorts to his renewed powers to bring Jason into his world. The battle ultimately spills out from the dream world into the real world. Though Lori Campbell tries to help Jason in defeating Freddy, both Jason and Freddy fall into the water and die; Jason from massive wounds and Freddy by Jason impaling him with Freddy's own arm before being beheaded by Lori with Jason's machete.
Jason is later seen leaving the lake with Freddy's severed head in tow. Because the head is seen winking, the nature of who won remains ambiguous.
The tenth film establishes that in the relatively near-future, Jason is being held as a prisoner in the Crystal Lake Research Facility (presumably built on the site of what was once Camp Crystal Lake). After several failed attempts to execute Voorhees, it is decided that he shall be held in cryonic suspension. Jason briefly escapes when the military attempts to take him away (presumably for use as a weapon) but is eventually trapped in a freezing chamber. Over four hundred years later, after Earth has become uninhabitable and its populace relocated to "Earth Two", Jason is found, still frozen, by a ship populated by students and soldiers. After being brought on board, and assumed dead, he thaws and begins killing as usual until he is effectively stopped by an android who destroys large portions of his body. His remains are abandoned on a bed used to help regenerate tissue via nanotechnology. Using the metal around them, the nanotechnology helps to rebuild Jason with an armored body, providing him more strength and seeming invulnerability, this new Jason is referred to as "Über-Jason" in the credits of the movie. The remaining survivors of the ship exhaust every effort to hold him back and eventually escape, leaving Über-Jason on a doomed space vessel. Jason apparently survives the vacuum of space to attempt an attack on the rescue ship but is tackled into Earth Two's atmosphere by a surviving soldier in a space-suit.
Jason is shown then burning-up upon entering Earth Two's atmosphere, although his hockey mask at least is shown to have survived the crash, ending its descent at the bottom of a body of water. Jason's fate after this incident has so far only been addressed in comics and novels, which are not necessarily canon. However, even if he is alive (and in one piece) it will take some time for even Jason to recuperate (even based upon his argued "recuperating abilities").