Am good writings!
Tolkien, of course. He's just...amazing.
Glen Cook is right up there with Tolkien, in my book. His world is just as developed, and he isn't afraid to be dark and gritty. And oh sweet momma how I love dark and gritty.
Neal Stephenson is rad, rad author. Cryptonomicon is so enthralling that, though it's 900+ pages, I've read it several times.
And while we're on -nomicons, Lovecraft is right fine as well.