I came across it last year when looking for books for the beach. Its quite a hefty book

Another vote for The Best of Lovecraft. The Dexter Ward story in particular is outstanding.

Imajica is well worth a read, but I wouldn't call it a horror. More dark fantasy if anything. Still fantastic though.

Yeah, I call it Fantasy Horror. I think there are quite a few horror elements (gruesomeness, gore, bad-doings in detail) and it needs to be in the categorization, but it definitely has a strong fantasy element, but not typical fantasy in any way. The dark and grit of London adds to the atmosphere, it's really not to be missed for horror reading fans, or fans of great literature even (beautiful writing - it's one of my favorite books) It's also strongly a love story.

More on the subject of horror books:

Lovecraft has great stories and ideas but they aren't the most developed or well-written horror of what I've read anyway.

Pick up a book of Poe and read whatever appeals. He almost goes without saying perhaps that is why no one has said him? (unless I missed it) The Pit and the Pendulum. The Fall of the House of Usher. anything

Piers Anthony has a book called Firefly, it is erotic horror/thriller, and one of my favorite books ever.

I suppose we shouldn't be surprised that Imajica is being adapted for TV. I hope they do a good job on it. There have been a fair few good TV adaptations of late so I have reasonably high hopes for it.

The Bible. Has quite some horror scenes in it!

Even better, I hate skinny books because by the time you get into the story, it's over. :)

Oh dear, Son. Now you got me started!
Horror is probably my favourite genre, in anything! Books, movies, games, etc.
I've read a good number of horror and horror related fiction over the years, so here are a few which I think are dandy! ;)

Seeing as Stephen King has been mentioned a few times, let's start with those:

The Stand - largely considered King's greatest work, a very lengthy, meaty apocalypse , zombie/infected story that'll definitely stick with you. Some people complain about the length, but that in part is what makes it so great. The sheer amount of time that you spend with these characters makes it all the better imo. Probably one of the best King works to delve into, if you haven't read anything else by him.

IT - Already mentioned a few times. IT is a very nostalgic book for me, and contains a lot of themes that King explores in other books, but arguably he does it best here. Also a very long book, IT covers two sides of the same story - the childhood lives of a group of friends, as well as their return as adults. There are a few... shall we say 'questionable choices' in IT though, which for me, take away some of the overall impact. All in all, though a great book!

The Shining - If you've seen Stanley Kubrick's film adaption, don't come in expecting the same sort of thing. While I adore Kubrick's Shining and consider it one of the best horror films of all time, it certainly took some liberties with King's original story. Again, not bad just different. The book has a lot more supernatural elements to it, as opposed to the movies implication that the majority was just Jack's growing insanity.
The book covers some great themes though, including fatherhood, alcoholism and isolation, along with the horror side - of course!

Moving onto Clive Barker:

I really think the best place to start with Clive Barker is his 'Books of Blood', which are his collections of horror short stories. While Barker's novels are also great, I've always rather liked his short fiction most. Probably because he has so many different, creative, often gruesome ideas, and you can get a real taste for his style, while still experiencing a wide variety of different pieces.
You can generally get the Books of Blood in two omnibus editions, the first collection vol 1-3 and the second vol 4-6.

As for his novels, The Damnation Game is probably his seminal horror novel, very much similar in style to his short fiction.
There's also 'A Hellbound Heart' - which is the novella that Hellraiser was based on. Personally, I'm not a big fan of it, but I know that some people love it.
There's also Cabal, which is a zombie novella, also made into the movie which recently got re-released with the much anticipated director's or 'Cabal' cut.

On Imajica - I don't know if I'd consider it horror, dark fantasy certainly, but not so much horror, though it does contain some horror elements. If, however it sounds appealing to you, you most definitely should read it! Barker considers it his magnum opus and for good reason. Imajica retains the dark, visceral style of his other work, but this one has so much more substance and depth. A lot of Barker's other work is good, but doesn't always leave a huge lasting impression. Imajica most assuredly will.

Jack Ketchum - a very underrated writer, who King has said to be 'the most important writer in America, other than maybe Cormac McCarthy.
All of his books are very different, some even seem like they're written by a different author, at first glance. The thing that makes Ketchum's work so great though is the fact that unlike, King, or Barker, or so many others, his work is largely based in reality. There are no supernatural occurrences. Not monsters or phantoms. Everything that happens is 'real'.

In fact, his most famous work, 'The Girl Next Door' (not to be confused with the romantic comedy), was actually based on true events, which makes it all the more chilling.
Ketchum is not for the feint of heart though, so I'd recommend looking up the summaries of his work first to see if it's for you.

Peter Straub is an interesting writer if you want someone similar to King, but still pretty unique.
(King and Straub are actually friends and have even collaborated on two books together)
Probably his best book, and the one I recommend most is 'Ghost Story'
It's sort of a 'small town ghost story' adventure, in which a group of old friends meet up and tell ghost stories, until one of them suddenly dies and the others begin to get haunted by it. It's a surprisingly deep novel and has a lot of different points of view and explores the characters backstories and everything that 'led up to' the present. It has a lot of charm, if you like that style and is one I recommend for something a bit different.

He also wrote 'Lost Boy, Lost Girl' and its sequel 'In the Night Room', which I liked, but nowhere near as much as Ghost Story.

Some others have mentioned King's son Joe Hill.
While I enjoyed Hill's books, overall I never 'loved' his work. He feels sort of like a more modern King, but not as good, imo.
Heart Shaped Box and Horns are of course his most notable books and are interesting, probably worth reading at least once, but I think his best work is his short story collection '20th Century Ghosts'!

If you're in the mood for some vampires, the obvious choices are of course,
Anne Rice's series, beginning with the fairly well know 'Interview with a Vampire'.
There's also 'Let the Right One in' by John Ajvide Lindqvist which is a personal favourite of mine - but it's more of a romance story with vampires, than a real 'horror'... oh, and it's nothing like Twilight! ;)

Speaking of Lindqvist, his other novel 'Handling the Undead' is also pretty good.

If you're into something completely different, and a little abstract, there's House of Leaves by Mark Z. Danielewski which will be unlike anything you've read before. There's not really a lot I can say about it, without ruining some of the initial surprise. Definitely consider checking this out!

A few other names worth mentioning who are from the 'Splatterpunk' subgenre, other than Barker and Ketchum is Edward Lee and the late Richard Laymon. Both are good, but don't stand out quite as much. Certainly worth a look, but not a whole lot to say about them.

Neil Gaiman is also worth mentioning. I'd recommend 'American Gods', though I guess it'd be considered more dark fantasy than horror. It's a really good book though and not worth overlooking. Coraline, I guess is a little more 'horor' but keep in mind it was written for a younger audience. His Sandman comics also probably fit.

If you're into older fiction, there is of course, the previously mentioned H.P. Lovecraft, as well as Edgar Allen Poe.
There's Psycho by Robert Bloch, Something Wicked this Way Comes by Ray Bradbury and of course Dracular by Bram Stoker.

Okay well, I'm runnin' out o' time, so hopefully you, or someone finds that useful!
Enjoy! :)

Victorian Horror Stories.
Victorian Ghost Stories.
They are collection of spine chilling stories. "One Silver Bullet" was on of my favorite.

Bump.

The original Dracula by Bram Stoker.

at the mountains of madness, hp lovecraft.

have not read the entire thing, but from the bots i've read, its pure brilliance, and has been regarded as a true classic of the genre.

Bump.

There are book that can horrify you just by looking at their name and cover.

http://www.amazon.ca/Justin-Bieber-Fever-Marc-Shapiro/dp/0312678789/ref=sr_1_2?s=books&ie=UTF8&qid=1433678197&sr=1-2&keywords=justin+bieber

Another vote for Lovecraft.

I used to love horror novels, but as I've gotten older it's hard to find books I really enjoy. I want to be scared for the protagonists, or at least feel a sense of unease, and these days that doesn't seem to happen often for me. "Horror" seems to mean so many things, and I don't like most of them.