Well it's not Halloween anymore but I do love horror so I will recommend some things for you.
Strange Circus and Tag (both are by Sion Sono) - both really weird and messed up, don't say I didn't warn you
Visitor Q - about a very disturbing family who break all the rules of normal society
Noroi: The Curse - the good kind of found footage
Bedevilled - very gory and makes you appreciate the feminist movement
Pulse aka Kairo - interesting take on the early internet
Battle Royale - it's fun to try and guess who will survive
And some western horror if you are interested.
Videodrome - conspiracy + sci-fi + horror = a good time
Eraserhead - I don't know why but the lady in the radiator creeps me out to this day
Dead Alive aka Braindead - arguably the goriest film in existence + very funny
Dead of Night: an oldie but the best horror anthology I've seen
Hereditary: this should hit your paranoid meter, I rarely get scared at horror films but this one had me messed up so bad I was afraid to go to sleep