Hm ... maybe Gene Roddenberry? "Star Trek" was the first TV show I remember watching, and the first to make me want to creat stories of my own.
No -- the single person who influenced me the most would be my father, who brought home comic books, probably pointed me toward "Star Trek" to begin with, and bought me that collection of Baum's Oz books. Planting that love of reading into a young kid can result in all sorts of strange and wonderful side effects ...