As I said last year when Kurt Vonnegut died, I don't like it when I score points for the death of someone who's work I admire.
 
Arthur C Clarke might not have been consistently the best science fiction author, but he wrote some amazing  books. When he worked on the 2001 film with Stanley Kubrick, he became part of one of the most influential SF films ever.
 
His early classic books include the amazing City and the Stars and Childhoods End. He also wrote about a matrix-like world of virtual reality in a short story, but I can't remember its name.
 
[Edit: I think it was the Lions of Comarre, where a computer in a mysterious city lets people live through their own 'dreamed' version of reality]