Friday the 13th

Sean Cunningham placed an advertisement for the title in Variety before there was a script, to find out whether anybody wanted it. Enough people did.

What it adds to Carpenter's template is gore. Tom Savini took the job because it was work and delivered the arrow through Kevin Bacon's throat, which was achieved with an appliance neck, a tube and Bacon lying under a false bed with his head through a hole while somebody pumped blood.

The reveal is a genuine surprise on a first viewing and has been spoiled for everyone since by four decades of parody. Jason is not in it in any meaningful sense; he appears in the last shot and only becomes the killer in the sequel.

Sequels aside, this is a competently made, cynical, extremely effective piece of product, and its success is the reason the next five years produced a slasher for every holiday on the calendar.