It was a fiendishly simple idea. Take a busload of horny teens to a remote campsite, unleash a homicidal maniac with a grudge, give make-up legend Tom Savini the keys to the gore cupboard, and - hey psycho! - it's the start of a brute-iful franchise. So pack your cozzie and keep the first aid kit handy because we're off to Lake Crystal, where something went horribly wrong with a boy called Jason...
Sean S. Cunningham
After Halloween became the then-biggest independent movie of all time, original Last House on the Left producer Sean S. Cunningham sniffed huge cash-in potential and placed a full page ad in Variety announcing Friday the 13th as "The Most Terrifying Movie Ever Made".
Expecting a respectable mortgage-paying mid-range hit, Cunningham watched his baby grow one of horror cinema's most enduring franchises.
So any horror fan bemoaning 2009's Friday the 13th remake as yet another example of imagination-free money men mauling a genre treasure should rewatch this 1980 movie.
Shamelessly cannibalising Halloween, Psycho, Carrie, Jaws, and even Bill Murray's Meatballs, calling Friday the 13th the "original" movie runs the risk of breaching the Trade Descriptions Act.
What it should be remembered for is solidifying (or embalming) the seven deadly slasher movie conventions:
Rule 1: Set the film around a famous calendar date.
Rule 2: Pick a young, attractive (and cheap) cast and have them do stupid things as the bodies pile up. For added fun play spot the star of the future - here Kevin Bacon.
Rule 3: Locate the action in a setting where adult help is not readily available - home alone, summer camps, abandoned mine shafts, schools after dark, colleges out of a term time.
Rule 4: Make extensive use of POV camerawork to disguise the killer / place the audience vicariously in the moment / reduce the actor's shooting schedule and save money.
Rule 5: Root the motivation for the murders in a wrong committed long ago.
Rule 6: For respectability cast a name actor in an extended cameo - here US TV darling Betsy Palmer.
Rule 7: Include a healthy ration of softcore nudity and hardcore gore.
And an optional Rule 8, handy for sequels: Make the killer indestructible.
Victor Miller's script features all these (even the 8th rule, in a way), centring the story around the re-opening of Camp Crystal Lake (aka Camp Blood) long closed since a terrible tragedy that for some reason the locals never feel obliged to tell newcomers about.
A group of camp counsellors set about renovating the dilapidated huts, but during one stormy Friday 13th are slain in a variety of outlandish ways.
Whereas Halloween and The Texas Chain Saw Massacre deserve their places in the pantheon of horror cinema, Friday the 13th's reputation is due largely to its eye-catching title.
Cunningham is a shrewd businessman but could not direct traffic, leaving long stretches of dead air between the violence and failing to muster any pre-brutality suspense.
And while the gore had them gasping and cheering in the aisles back in the innocent early 80s, audiences today will be surprised (possibly bored) by the movie's quaintness and astounded at the low quotient of grue, particularly as make-up genius Tom Savini is on latex duty.
The final reel reveal of the killer (not Jason) kicks the film into a higher gear, before a Carrie-style shock ending (suggested by make-up man Savini) kind of sets up Jason as the killer for the next instalment. Although the hockey mask was not introduced until Part 3.
Not even the best Friday the 13th movie (that would be Part IV or Jason X), this movie's largest achievement was in making mainstream Hollywood sit-up and embrace the slasher genre - with distributor Paramount making a killing off the movie.
Whether the resulting slew of calendar themed carnage carnivals - Prom Night, New Year's Evil, My Bloody Valentine, Silent Night, Deadly Night, Mother's Day - plus the endless FT13th sequels was worth it remains hotly debated.