They are...
Psycho
Night Of The Living Dead
The Texas Chainsaw Massacre
Each one seemed to mark a pivot point in the genre. All three highly influential. The first two are generally more highly praised than the third, yet chainsaw is my personal favorite of the three.
I'd even add The Exorcist. It pivoted the whole possession aspect of horror.
shareI feel like the distinction of the film that redefined horror in the 70s is either given to TCM or Halloween. I feel like although TCM is a much scarier film, Halloween was probably more overtly influential because it was a box office hit. TCM was seminal, there's no doubt, but Halloween is probably the reason we have Friday the 13th and the Elm Street films. If you're going to get really analytical, you could even bring Black Christmas into it, and say that pre-dated Halloween in establishing the modern slasher tropes.
But none of the films before or after the original Texas Chain Saw Massacre equal its power in being an absolutely merciless, uncompromisingly disturbing experience. It was one of the very few films that has ever actually scared me and that's a pretty bold statement because I used to be a horror fanatic.
1) TCM 2) Halloween 3) Excorsist
I would throw the Blair Witch Project in there. It wasn't the first found footage film but it was the first to really capture the mainstream audiences attention and kick started the craze. It's kind of similar r to what Halloween did for the slasher genre.
"Notice how I ride side saddle, it proves I'm a lady of quality." Witch Hazel
I enjoyed The Blair Witch Project but the found footage films quickly became stale soon after in my opinion.
share🤮
shareYou can kind of see the influence of each horror cornerstone:
Psycho - psychological thrillers like Silence of the Lambs, Dressed to Kill, etc.
Night of the Living Dead - zombie/apocalypse films
The Exorcist - supernatural horror such as The Omen, Carrie, Amityville, Conjuring
Texas Chain Saw Massacre and Halloween - masked slasher films like Friday the 13th, Nightmare on Elm Street, Scream, etc.
The Shining - “deep” horror such as Hereditary, The Witch, Neon Demon, etc.
I would say
NotLD
TCM
Black Christmas