Starship Troopers is a military science fiction novel by American writer Robert A. Heinlein. Written in a few weeks in reaction to the US suspending nuclear tests, the story was first published as a two-part serial in The Magazine of Fantasy & Science Fiction as Starship Soldier, and published as a book by G. P. Putnam's Sons in December 1959.

The story is set in a future society ruled by a human interstellar government dominated by a military elite, referred to as the Terran Federation. The first-person narrative follows Juan "Johnny" Rico through his military service in the Mobile Infantry. Rico progresses from recruit to officer against the backdrop of an interstellar war between humans and an alien species known as "Arachnids" or "Bugs". Interspersed with the primary plot are classroom scenes in which Rico and others discuss philosophical and moral issues, including aspects of suffrage, civic virtue, juvenile delinquency, and war; these discussions have been described as expounding Heinlein's own political views. Starship Troopers has been identified with a tradition of militarism in US science fiction, and draws parallels between the conflict between humans and the Bugs, and the Cold War. A coming-of-age novel, Starship Troopers also critiques US society of the 1950s, arguing that a lack of discipline had led to a moral decline, and advocates corporal and capital punishment.

Starship Troopers brought to an end Heinlein's series of juvenile novels. It became one of his best-selling books, and is considered his most widely known work. It won the Hugo Award for Best Novel in 1960, and garnered praise from reviewers for its scenes of training and combat and its visualization of a future military. It also became enormously controversial because of the political views it seemed to support. Reviewers were strongly critical of the book's intentional glorification of the military, an aspect described as propaganda and likened to recruitment. The ideology of militarism and the fact that only military veterans had the right to vote in the novel's fictional society led to it being frequently described as fascist. Others disagree, arguing that Heinlein was only exploring the idea of limiting the right to vote to a certain group of people. Heinlein's depiction of gender has also been questioned, while reviewers have said that the terms used to describe the aliens were akin to racial epithets.

Despite the controversy, Starship Troopers had wide influence both within and outside science fiction. Ken MacLeod stated that "the political strand in [science fiction] can be described as a dialogue with Heinlein". Science fiction critic Darko Suvin wrote that Starship Troopers is the "ancestral text of US science fiction militarism" and that it shaped the debate about the role of the military in society for many years. The novel has been credited with popularizing the idea of powered armor, which has since become a recurring feature in science fiction books and films, as well as an object of scientific research. Heinlein's depiction of a futuristic military was also influential. Later science fiction books, such as Joe Haldeman's 1974 anti-war novel The Forever War, have been described as reactions to Starship Troopers. The story has been adapted several times, including in a 1997 film version directed by Paul Verhoeven with screenplay by Edward Neumeier that sought to satirize what the director saw as the fascist aspects of the novel.