I love horror, everything from Italian Giallos to zombies, exploitation and terrorisation.
Some I don’t think were mentioned:
Dawn of the dead - remake as well as the original. If you are watching the original there are several different versions and they are worth watching as the Argento cut with its Goblin soundtrack has a very different feel to Romero’s Cut.
Talking of Argento I can’t walk past a horror thread without recommending Deep Red (Profondo Rosso) and Suspiria (one of my favourite films and frequently in top 10 lists, well deserved).
No one lives, You’re next. I tend to double bill these, or did before I had children that woke every 30 minutes in the evening - they work nicely together.
Stake Land.
I seem alone in this thread but I love slashers. Some good ones that haven’t been mentioned- anything from the golden age ‘78 - 84: The Prowler, Black Christmas, When a Stranger calls, to the more notorious nasties like New York Ripper.
Australia have some really good examples - Wolf Creek (and its sequel), Storm Warning, Boar, The Stranger.
Martyrs (the french original not the American remake).
some really good English horrors recently, Eden Lake is one of the best I can think of, but also Howl, Tower Block, Comedown, Saint Maud, The Ritual.
It follows has been mentioned but it’s so good I have to mention it again.
I wish I could watch all of these for the first time again.