J.R.R. Tolkien’s posthumous book The Silmarillion was published in 1977.
Tolkien died in 1973, leaving behind a large and complex body of stories about the creation of the world, the Valar, the Elves, the First Age, and Númenor. His son Christopher Tolkien edited the manuscripts into a publishable volume, with assistance from the fantasy writer Guy Gavriel Kay.
The Silmarillion is not a conventional novel. It is a collection of mythic histories and related texts, including the Ainulindalë, Valaquenta, Quenta Silmarillion, Akallabêth, and Of the Rings of Power and the Third Age. The book gives background to figures and events that are only briefly mentioned in The Lord of the Rings.
Christopher’s editorial choices made the 1977 volume coherent, but Tolkien’s papers contained multiple versions and unresolved variations. Later volumes of The History of Middle-earth revealed more of that development. The title refers especially to the three Silmarils, jewels central to the history of the First Age.