Robert Anson Heinlein; numerous pseudonyms, notably Anson Macdonald) (1907-1988) was one of the most popular and influential science fiction writers of the twentieth century, often viewed as one of the "Big Three" authors with Arthur C. Clarke and Isaac Asimov. His work helped define the genre; Asimov referred to his work as "the third nova" of science fiction, an entry into the field that changed it substantially from that which came before.
His many novels included The Puppet Masters, Starship Troopers, The Moon is a Harsh Mistress, and Stranger in a Strange Land. He also wrote numerous novels for young people, often referred to as "Heinlein juveniles", including Double Star, Citizen of the Galaxy and Star Beast. (The fact they are written for young people does not mean that they only appeal to the young -- like many of the best works written for teenagers, they can be read, and are read, by adults.) Heinlein also authored many short stories, including "And He Built a Crooked House" and "All You Zombies."
His politics defied categorization. They were broadly libertarian. He was a strong supporter of the military, as shown in Starship Troopers and other works, and was an ardent opponent of Communism, demonstrated in an essay about his vacation in Soviet Russia, but also espoused the sexual revolution of the 1960s, as strongly shown in many of his later works, and alluded to in earlier ones, and was very skeptical of organized religion, especially fundamentalism, demonstrated in works like Job: A Comedy of Justice and the novella Revolt in 2100. His novel The Moon is a Harsh Mistress, the story of a Moon colony rebelling against a United Nations-run command economy in order to establish their own free market state, is a strong work of pro-capitalist, anti-UN science fiction.