While preparing my "The horrors of 2020" series (don't pin me down on that one!) I looked and asked online for people's favorite 2020 horror(ish) releases. And then I made this list!
The definition I used for a "2020 horror movie" isn't per se set in stone. You'll see a lot of 2019 release dates, but often this is during their initial festival run, almost all of these had an actual theatrical or home media release in 2020. I've added notes to the titles where this is debatable.
Finally, "horror" is a broad term, so I added about 99% of the titles I found, although some do come with a note about wether they're actually horror movies. Then again, it's just a Letterboxd-list/YouTube video series, not a scientific paper so I think we're all good :D