Which of J.R.R. Tolkien’s books was published posthumously in 1977 by Christopher Tolkien?

J.R.R. Tolkien’s The Silmarillion was published posthumously in 1977 by Christopher Tolkien.

The book presents the mythology and history of Tolkien’s imagined world, beginning with creation and continuing through the First Age and later events. It includes the creation of Arda, the history of the Valar, the wars against Morgoth, and stories involving figures such as Fëanor, Beren, Lúthien, and Túrin Turambar.

Tolkien died in 1973 without preparing a final publishable version. His son Christopher edited material from manuscripts and notes, with assistance from Guy Gavriel Kay, and assembled the published work. As a result, The Silmarillion is not a conventional novel with one continuous narrative voice.

It is often confused with Unfinished Tales, which appeared in 1980. The Silmarillion is the earlier posthumous collection and provides the broadest single overview of Tolkien’s mythology.