H.G. Wells
Terry Pratchett
J.R.R. Tolkein
Neil Gaiman
Those would be the four that I can go back to time and time again and still get something from. Strangely they're all fantasy/sci-fi but 90% of the books I read by other authors aren't in those genres. I usually find fantasy and sci-fi to be a bit silly (
) and, half the time, they're just a rip-off of Wells or Tolkein anyway.