Speculative fiction is an umbrella genre of fiction that encompasses all the subgenres that depart from realism, or strictly imitating everyday reality, instead presenting fantastical, supernatural, futuristic, or other imaginative realms. This catch-all genre includes, but is not limited to, science fiction, fantasy, horror, slipstream, magical realism, superhero fiction, alternate history, utopia and dystopia, fairy tales, steampunk, cyberpunk, weird fiction, and some apocalyptic and post-apocalyptic fiction. The term has been used for works of literature, film, television, drama, video games, radio, and their hybrids.

Fiction is any creative work, chiefly any narrative work, portraying individuals, events, or places that are imaginary or in ways that are imaginary. Fictional portrayals are thus inconsistent with history, fact, or plausibility. In a traditional narrow sense, "fiction" refers to written narratives in prose – often referring specifically to novels, novellas, and short stories. More broadly, however, fiction encompasses imaginary narratives expressed in any medium, including not just writings but also live theatrical performances, films, television programs, radio dramas, comics, role-playing games, and video games. The publishing industry divides fiction into adult fiction, young adult fiction, new adult fiction, and children's fiction.