Robert Anson Heinlein (/ˈhaɪnlaɪn/ HYNE-lyne; July 7, 1907 – May 8, 1988) was an American science fiction author, aeronautical engineer, and naval officer. Sometimes called the "dean of science fiction writers", he was among the first to emphasize scientific accuracy in his fiction and was thus a pioneer of the subgenre of hard science fiction. His published works, both fiction and non-fiction, express admiration for competence and emphasize the value of critical thinking. His plots often presented provocative situations which challenged conventional social mores. His work continues to have an influence on the science-fiction genre and on modern culture more generally.
Heinlein became one of the first American 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 are often considered the "Big Three" of English-language science fiction authors. Notable Heinlein works include Stranger in a Strange Land, Starship Troopers (which helped mold the space marine and mecha archetypes) and The Moon Is a Harsh Mistress. His work sometimes had controversial aspects, such as plural marriage in The Moon Is a Harsh Mistress, militarism in Starship Troopers and technologically competent women characters who were formidable, yet often stereotypically feminine—such as Friday.