I don't actually consider Stephen King horror. Then again, I'm pretty anti-King... not that I want anyone to quit liking him or anything crazy like that. I just can count the books I like of his on one hand. And two fingers. Maybe it's because my mom kept on pushing me to read him and screaming at me every time I put his books down because they were boring me.
My favorite author is definitely H.P. Lovecraft. Pessimistic, dreary, terrifying in their scope. Let's see, should I be more scared of Slenderman, Jigsaw, long-haired Japanese chicks, or a color out of space that can turn you into ash and you can't even see it. What about a squid-headed giant who is dead but can still fuck yo' shit up?
Kurt Vonnegut, Jr is another one. Witty, with an amazing grasp on human nature. His death was too sudden, he shall be missed in the realms of literature. Although Slaughterhouse Five is probably his most well known work, honestly, my favorites are Galapagos and Cat's Cradle.
H.G. Wells must be mentioned as well - rather like Lovecraft in his world view, except he rights more fantastical stuff than straight up horror. Are you a Morlock or an Eloi?
The Ender's Game series by Orson Scott Card is excellent sci-fi fiction, for the most part. I dislike how he handles romance, but my favorite book in the series is probably Xenocide.
I guess the most modern author I like is Pratchett. People rave him about him, and he's certainly funny, but I cringe when female characters are brought in. He plays the "they're hot and blonde and busty so everyone thinks they're attractive" card way too much, which gets on my nerves. Not everyone has the same physical interests, Terry Pratchett, trust me. Just because someone has a +20 in charisma doesn't mean they're going to be my type...
Ah, and Fannie Flagg. Fried Green Tomatoes at the Whistle Stop Cafe and I Can't Wait to Get to Heaven are equally wonderful heart-warming books. That's some lovely down home country spirit.