Robert Heinlein was a prolific science fiction writer responsible for many novels that addressed fundamental issues of his day and expressed predictions of society and its general direction. One of his more well known (and probably the most /tg/ related) novels is Starship Troopers, which (written in 1959) serves as the inspiration for "Space Marines" as a general concept, not that GW would ever admit that.
He began his adult life working as a naval officer for the U.S. military and conveniently came down with a case of tuberculosis in 1934 before the outbreak of the Second World War. He began his writing career soon after and many of his topics centered around certain social themes, including an individual's obligation to society and his own responsibility to remain self-reliant, the amount of influence that a major religion could exert onto a society, and the inevitable diaspora that pertains to humanity's ability to develop space travel. He's also responsible for creating almost all sci-fi clichés. His early works often contain a lot of Humanity Fuck Yeah, military thematics, glory, honor, and lots and lots of corpses, blood and violence, which pleases Khorne immensely. His late works (usually demarcated by Stranger In A Strange Land, the book that gave us the word "grok") also contain a disturbing amount of (what were considered at the time to be) sexual deviance, including polygamy, incest (okay, that's still deviant today), bi- and homosexuality, interracial and interspecies relations (which may or may not be considered deviant, depending which direction you go). A definite vibe of Slaanesh worship can be found in his books.
There are a few contributions that he did make to science fiction and by extension to fa/tg/uy culture itself such as:
- The "World-as-Myth" concept (the idea that all fictional settings exists out there in the omniverse as their own genuine realities).
- The word "Waldo" (meaning a remotely-operated manipulator arm).
- Created the first design for a waterbed (though never patented it).
- Many ideas and themes of 40K's Imperium of Man such as diaspora (see Age of Strife), religious government turning into an oppressive regime, persecution of mutants, and many of the negative effects of interplanetary space travel - not so much the Warp (that belongs firmly to H.P. Lovecraft) but more so the amount of cultural differences and the recurring theme of rebellion among governed planets.
- One of his characters, "Lazarus Long", did directly inspire Ollanius Pius.
- Power armor.
- Drop Pods.
- Spartan-training super-soldiers.
- Intelligent space-faring insectoid swarms.
- Parasite puppeteers.
- Almost a dozen types of post-apocalypse and grimdark futures - he did it all first.