Robert Anson Heinlein was an American science fiction writer. Often called "the dean of science fiction writers", he was one of the most popular, influential, and controversial authors of the genre. He set a high standard for science and engineering plausibility and helped to raise the genre's standards of literary quality. He was one of the first writers to break into mainstream, general magazines such as The Saturday Evening Post, in the late 1940s, with unvarnished science fiction. He was among the first authors of bestselling, novel-length science fiction in the modern, mass-market era. For many years, Heinlein, Isaac Asimov, and Arthur C. Clarke were known as the "Big Three" of science fiction.

Heinlein, who also served as an aeronautical engineer and naval officer, emphasized scientific accuracy in his fiction, making him a pioneer of hard science fiction. His work often posed provocative situations that challenged conventional social mores, continuing to influence the science-fiction genre and modern culture. Notable works include Stranger in a Strange Land, Starship Troopers, and The Moon Is a Harsh Mistress.

Heinlein was awarded the first Science Fiction Writers Grand Master title in 1974. Four of his novels won Hugo Awards, and he coined terms like "grok", "waldo", and "speculative fiction". He explored themes such as individual liberty, self-reliance, sexual relationships, and the role of religion in society.