Okay, I've established that I like me some horror. I don't really like definitive "Ten Best" lists (writing them anyway; I love reading them), so I'll just talk about seven I really like. Some are only loosely horror, but it's my list, so there!
1. The Arabian Nightmare - Robert Irwin
What a weird-ass book this is. A young Englishman comes to medieval Cairo during an epidemic. The victims fall into a never-ending nightmare that they can't remember if and when they wake. Balian, our protagonist, runs into various bizarre characters, such as Dirty Yoll the story-teller (who is also our narrator), possibly comes down with the nightmare, is victim of various conspiracies... It gets very strange, not least when the narrator dies, but keeps telling the story, and then gets better... maybe.
2. Needful Things - Stephen King
Look, I know many people think of this as one of King's worst works, but I love it. Besides, do you need yet another person extolling the virtues of IT, The Shining, or 'Salem's Lot? Of course not.
So, the devil comes to Castle Rock, promising the citizens their fondest wish if they'll just do him one small favor... The premise is awesome, the characters incredible, and some of the writing (particularly the prologue) is the best King has ever published. Scoff if you must, I love this book.
3. The Book of Skulls - Robert Silverberg
Four college kids go to the desert, seeking the cure for mortality. Two must die, so the others may live forever. Dark, hedonistic, philosophical, and amazing. Told from four different, first-person perspectives in such a way that you never get confused as to who is currently narrating. Brilliant.
4. The Haunting of Hill House - Shirley Jackson,Laura Miller
If you know anything about horror fiction, you've heard of this. Do yourself a favor and read it. Probably the best haunted house novel I've ever read.
5. The Off Season - Jack Cady
Another strange one. A wanderer comes to town, along with a cat who purrs in several languages. A Victorian-era madman comes back to life, promising to help the citizens make mucho moolah in the tourist trade by exploiting their many ghosts. There's a parsonage that never stays in the same place, only to become a flying fortress during the final battle. Whoa.
6. The Tomb (Adversary Cycle, #2) - F. Paul Wilson
First, and best, of the Repairman Jack series. Jack is hired to retrieve a strange necklace for an ancient Indian woman as all hell breaks loose in NYC. Action-packed with many memorable characters.
7. The Club Dumas - Arturo Pérez-Reverte,Sonia Soto
Got into this book after seeing the movie The Ninth Gate, which was loosely based on this.
A rare book dealer is hired for two different jobs: to track down the manuscript of a certain chapter from The Three Musketeers; and to find out which, if any, of the three remaining copies off an evil tome is the original, for unknown reasons. Dark, funny, suspenseful, this introduced me to one of my favorite authors. If you like swashbucklers, check out his Captain Alatriste novels.