The last of the big three has died. While of the three (Heinlein, Asimov, and Clarke) he was my least favorite, that's hardly a condemnation considering his contemporaries. He wrote 2001, A space Odyssey, 2010, Rendezvous with Rama, and many other greats. He even originated the idea of geosynchronous orbit.
He was a visionary and he dared us to look beyond the horizons of our little planet and into space.