William Faulkner. His stream of consciousness style is something I identify with very strongly. Many of his stories include elements of the grotesque which I love. I enjoy Sherwood Anderson for the same reason. And for lagniappe, I'll just throw in Flanner O'Connor, too :)
As far as a modern writer, I'd say Cormac McCarthy. For many of the same reasons that I enjoy Faulkner.