Sean S. Cunningham
Well, if LHOTL isn't made, Friday the 13th may never have happened. The reason: Sean S. Cunningham. He was the Producer and Director of that movie. If he never had anything to do with Last House, he would have never had anything to do with Friday the 13th, and who knows? Maybe no Freddy Kreuger or other movies that may have been influenced in a small way by Friday the 13th.
Also, one less movie would be remade today(why are we remaking films in the first place).