When I was growing up it was generally considered that the three greatest science fiction writers were Isaac Asimov, Robert A. Heinlein, and Arthur C. Clarke. (Some would add Andre Norton, Poul Anderson, and Ray Bradbury to the list. I won't dispute any of them.) Clarke, last of my three old favorites, died this morning.
You'll find obits on MSNBC, The Telegraph, and the BBC, as well as damned near everyplace on the Web and on my friends list.
There's not much more I can say.