Space opera is a subgenre of science fiction that emphasizes space warfare, with use of melodramatic, risk-taking space adventures, relationships, and chivalric romance. Set mainly or entirely in outer space, it features technological and social advancements in faster-than-light travel, futuristic weapons, and sophisticated technology, on a backdrop of galactic empires and interstellar wars with fictional aliens, often in fictional galaxies. The term does not refer to opera music, but instead originally referred to the melodrama, scope, and formulaicness of operas, much as used in "horse opera", a 1930s phrase for a clichéd and formulaic Western film, and "soap opera", a melodramatic television series. Space operas emerged in the 1930s and continue to be produced in literature, film, comics, television, video games and board games.

Science fiction is a genre of speculative fiction, which typically deals with imaginative and futuristic concepts such as advanced science and technology, space exploration, time travel, parallel universes, and extraterrestrial life. It is related to fantasy, horror, and superhero fiction and contains many subgenres. Its exact definition has long been disputed among authors, critics, scholars, and readers.