I first read "DRACULA by Bram Stoker when I was about 13, all in one night. Oh, and what a night.... I don't know how I did it, either, since it's a very dense novel, in my estimation. I still read it, in parts, over and over. I love it.

When I discovered Project Gutenberg, and found that I could download other Stoker novels, I did just that!

I read LAIR OF THE WHITE WORM (I love the movie) and... well... It wasn't as accessible as I thought it might be. THE LADY OF THE SHROUD is better... but Drac is still his ultimate best. Truly innovative, a fun read... so rich in character... and, of course, spoooky.

The Project Gutenberg, for those who don't know about it, can be found here:

promo.net/pg/

For me, it was back in High School. I had a great creative writing class and the teacher knew I was a huge Steven King and Peter Straub fan. He suggested checking out HP Lovecraft, and I was hooked. I have thanked him many times for pointing me in Lovecraft's direction. Although the tons of money I have spent collecting his works, sometimes leaves me on the Ramen Noodle Diet, but well worth it.

Ambrose Bierce (anyone read the Devil's Dictionary?)
Arthur Conan Doyle
Lovecraft and Poe, of course
Stephen Crane wrote some good horror stories
Manley Wade Wellman

And I agree about Matheson -- while not exactly "classic" he definitely is one to read and experience. Ray Bradbury would also have to be included, though, imho.

I also think that some credit needs to be given to the Brothers Grimm...