We'd literally be here all day if i we're to list every last Horror film that i love, so I'll go ahead and do EVERYONE a favor by narrowing down the selection, and listing my essentials...
The Shining - It traumatized me at 5 years old and i still love it.
Halloween - No comment needed.
Eraserhead - the overall bleak feeling just leaves you creeped out.
The Evil Dead trilogy - Dark comedy/horror at it's finest.
The Blair Witch Project - Love it or hate it, it was a breath of fresh air at the time..
In the Mouth of Madness - So much depth and so many horrific visuals..
The Sentinel - A fine forgotten horror film with many nightmarish moments
Jacob's Ladder - Damn.