What about Frank Herbert? The Dune books are in the realms of creative art. Then there is Tolkein and his hobbits. LOTR brought a new dimension to fantasy as well as marking Tolkein the only writer who really ever managed to get away with successfully writing in omni.

John Wyndham wrote a goodly many that became films and then there are Huxley and Orwell, both of whom had books used in curriculi.

I guess the guy who started it all was H.G.Wells. He surely deserves a mention.

I don't see the great ladies mentioned. The first great lady coming to mind is Andre Norton. Then what about Marian Zimmer Bradley and Anne McCaffrey?