For those interested, I compiled an "alternative" list of 31 horror movies, which includes but isn't limited to atmospheric slow burns, sci-fi horror, barely tangentially horror, traditional horror but arguably hidden gems, not scary at all and arguably comedy horror, and anthologies. The common threads are they're not likely to show up in a "best horror movies" list, they're all available for streaming or rental on the major services, and I think they're good. Its purpose is to give you ideas for movies to watch if you've already seen the major franchises, The Shining, The Thing, etc. Again, some of these are only tangentially horror, and some aren't meant to be scary, so do some quick non-spoiler research before you watch so you aren't unpleasantly surprised due to having the wrong expectations.
I cut a couple of more well known titles from the list to get it down to 31, which you should watch first if you haven't seen yet, including The Witch, Hereditary, Let the Right One In, and Train to Busan
Posting mid-September rather than October 1st since it's probably tough to get this many movies in for one month
The List:
The Orphanage (subtitles)
The Wailing (subtitles)
The Blackcoat's Daughter
The Empty Man
The Ritual
V/H/S
Southbound
[REC]
Event Horizon
Suspiria (2018)
Climax (subtitles)
Under the Skin
Terrified (subtitles)
In the Mouth of Madness
Creep
Inside (2007) (subtitles)
One Cut of the Dead (subtitles)
Cube
Kill List
Starry Eyes
High Tension
Henry: Portrait of a Serial Killer
The Neon Demon
The Wolf of Snow Hollow
A Dark Song
Audition (subtitles)
The Love Witch
A Tale of Two Sisters (subtitles)
Blood and Black Lace
Beyond the Gates
Under the Shadow (subtitles)