My Triumvirate of favorite authors is:
Robert Heinlein - favorite inside joke with my friends comes from him: "Do you Grok me, motherf----r?!"
J.R. Ward - the Black Dagger Brotherhood was suggested to me by a friend, and while it started out like a standard vampire romance story, it shifted rapidly into horror/action/drama the likes of which I've not seen since my third fav...
George R.R. Martin - When you've absolutely, positively had enough of elves, dwarves, halflings and happily-ever-after fantasy. Accept no substitutes.
Others worth mentioning: Hero (Perry Moore, young adult), Magic's Pawn (Mercedes Lackey, semi-YA), The Malazan Book of the Fallen (fantasy balanced between Martin's brutality and Tolkien's whimsical; 14 books long, with at least one more Epilogue book to go), Redwall series (made my childhood), and let's just throw in Suzanne Brockmann's Troubleshooter series for good measure.