Robert A. Heinlein autographing at the 1976 Midmericon.

Robert Heinlein (July 7, 1907 – May 8, 1988) is considered by many to be one of the "Big Three" authors of Science Fiction. He, along with Isaac Asimov and Arthur C. Clarke were the three major, prolific proponents in the early years, the 1940s, 50's, and 60's, and they are generally considered the fathers of modern Science Fiction.

Much more detail can be found at the Wikipedia article.

He has written many science fiction books including