This is a fun article from io9, on authors who are/were so distinctive that they defined entire sections of genre fiction, in both film and on the page. I was interested to discover a few new names (am I too sheltered?) and to see a few classics left off the list (Lovecraft, Robert E. Howard, Tolkien):
Some people don't just create new worlds and super-memorable characters — they give life to their own genres. There are some creators of fantastical stories whose work is so distinctive, you have a pretty good sense what's going to happen when you pick up their work — and you're excited, because it's going to be a hell of a ride.