Ray Bradbury
One of the first major events I ever attended as a publishing professional--as an editorial assistant at Bantam Books--was a cocktail party at the corporate offices in honor of Ray Bradbury being named a SFWA Grand Master at the Nebula Awards. My boss handed me a roll of name labels and a magic marker, and instructed me to distribute the tags as a way to introduce myself and get to know people. (Smart guy.) I walked up to a group of three men standing together. One was a distinguished gentleman with a goatee--Robert Silverberg. One was a scruffy fellow with sparkly eyes and a great wit--Geoge Alec Effinger. The third was a big man with a thick head of white hair, one Ray Bradbury, whose work I'd read in school and seen adapted for television. It was one of the few times I've ever been at a loss for words. He was gracious to a neophyte, and I've never forgotten that one encounter with him. His works changed the genre and the world. He will be missed.