Charles Bukowski. Buk wrote with the engaging laser-beam simplicity of Elmore Leonard, and pulled no punches with language, subject matter, and attitude. But whereas Leonard actually followed conventional ideas about story arc, plotting, and character development, Buk often wrote entire novels where, in alcoholic Seinfeldian fashion, nothing ever really happened. And I adore that. (On the other hand, he was a total downer, which I strive not to be.)
Jack Kerouac's "Visions of Cody". The only Kerouac novel I really have any use for anymore (okay, "Desolation Angels" is pretty good too) is the one that most of his hippiefied fans would prefer to forget: it's a huge doorstop of a politically-incorrect stream-of-consciousness tome that tells no story, yet tells ten thousand anecdotes in the process of telling no story. You don't even need to read it linearly - like the Bible, you can just open it anywhere and dive in to its random rambling prose. It's all about texture, that feel, that indefinable "it."
Douglas Adams. Say what? Yeah. I think he's one of the greatest writers of the 20th century. If you disagree, my own writing is probably not for you. Adams systematically tossed out into the dustbin most of the established rules for so-called "good writing", and yet spawned a multi-book best-seller empire that branched out into radio, TV and movies. His characters stand around chit-chatting, then a way-too-clever narrator bloviates densely for pages on side tangents, then the characters chit-chat some more. Then something explodes. Or maybe it doesn't. End of story. It was never about plot, but all about the chit-chat. I love it.
Franklin W. Dixon. I know, I know, he's not a real person, but man, that just makes it 673% awesomer. And when I say Dixon's name, I mean to include all imaginary authors who penned children's novels by the pound rather than the word. Hardy Boys, Nancy Drew, Tom Swift, Bobbsey Twins, I eat it all. This also includes all the glorious pulp fiction authors of the first half of the 20th century, plus peculiar Big Little Books, idiosyncratic Gold Key Comics and half-baked radio dramas.
William S. Burroughs. Though WSB was a rather loathesome person in life, devoting most of it to pursuits such as drugs, sexual perversion, and wallowing in self-pity, I have a fondness for his very early ("Junky", "Queer") and very late ("The Place of Dead Roads") works. All that lazy surrealist cut-up stuff in the middle that pretentious professors pretend is precious ("Naked Lunch", "Soft Machine", "Wild Boys"), well, not so much. Kerouac did stream-of-consciousness better, and for that matter, so did James Joyce. Furthermore, many of WSB's best moments were actually influenced by/borrowed from greater men than himself - but that bothers me not. I borrow from his borrowings, and so goes this thing of ours.
Harry Stephen Keeler. This is where we really separate the grumps from the mugwumps. Keeler is fetishized in certain circles as being "the Ed Wood of literature" - namely that he's "soooo bad, he's good." Well, in the first place, Jack, ED WOOD was the Ed Wood of literature - he wrote novels himself, you know - and in the second place, I do not subscribe to the concept of "camp" or "kitsch". I find Keeler to be a flat-out genius, and wholly worthy of legitimate praise - not the "this guy is terrible but he's hilarious! hahaha!" sort. Again, you have been warned.
Thomas DeQuincey. Sometimes, just for kicks, I assume the beingness of DeQuincey, and I derive great satisfaction from it. Your mileage may vary. Don't say I didn't tell you so.