Although Jason is supposed to be a fictitious character, there are striking similarities in the film to a series of grisly murders in Finland in the summer of 1960. Three teens were stabbed to death while camping at Lake Bodom.
The original film's director and co-writer John Carpenter (who also co-wrote 1981's Halloween II with his writing and producing partner Debra Hill) says a creepy encounter he had while attending Western Kentucky University served as inspiration for the fictional serial killer.