Robert Anson Heinlein (July 7, 1907 – May 8, 1988) was an American science fiction writer. Often called the "dean of science fiction writers", he was one of the most influential and controversial authors of the genre. He set a standard for science and engineering plausibility and helped to raise the genre's standards of literary quality. He was one of the first science fiction writers to break into mainstream magazines such as The Saturday Evening Post in the late 1940s. He was one of the best selling science fiction novelists for many decades. Heinlein, Isaac Asimov and Arthur C. Clarke were known as the "Big Three" of science fiction.