What makes a good horror novel

I was thinking about some of my favorite horror authors the other day and what their various strengths are in writing.  Bram Stoker for instance, he wrote the quintessential vampire novel with Dracula.  He gave Dracula certain powers that made him very formidable but also just enough weakness to be exploited.  The remoteness of the Carpathian Mountains in the 1880's made for its own set of challenges as well.  Stephen King creates very memorable characters who are very earthy and gritty at times but share feelings we all find we have in common.  James Herbert created certain moods through vivid description and could terrify you just as easily through very detailed and often gory scenes.

Who are some of your favorite horror authors and what books by them are among your favorites?  I'll start with a few of mine.

F. Paul Wilson, his novel The Keep is one of my all time favorites.

James Herbert, The Ghosts of Sleath, the 2nd of the Ash books, is a very scary read.

Stephen King, Salem's Lot is one of the best vampire novels since Dracula.