Mythopoeia (also mythopoesis, after Hellenistic Greek μυθοποιία, μυθοποίησις "myth-making") is a narrative genre in modern literature and film where a fictional or artificial mythology is created by the writer of prose or other fiction. This meaning of the word mythopoeia follows its use by J. R. R. Tolkien in the 1930s. The authors in this genre integrate traditional mythological themes and archetypes into fiction.
Mythopoeia is also the act of making (creating) mythologies. Notable mythopoeic authors include Tolkien, C. S. Lewis, William Blake, H. P. Lovecraft, Lord Dunsany, Mervyn Peake and George MacDonald. While many literary works carry mythic themes, only a few approach the dense self-referentiality and purpose of mythopoeia. It is invented mythology that, rather than arising out of centuries of oral tradition, are penned over a short period of time by a single author or small group of collaborators.
As distinguished from fantasy worlds or fictional universes aimed at the evocation of detailed worlds with well-ordered histories, geographies, and laws of nature, mythopoeia aims at imitating and including real-world mythology, specifically created to bring mythology to modern readers, and/or to add credibility and literary depth to fictional worlds in fantasy or science fiction books and movies.