While the franchise's production team has largely denied taking inspiration from any real-life events, a massacre in 1960s Finland shares eerily similar details with the movies. These similarities have fueled speculation that this is where the story in Friday the 13th came from.

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.