Who edited and completed the posthumously published book The Silmarillion?

Christopher Tolkien edited and completed the posthumously published book The Silmarillion.

J.R.R. Tolkien died in 1973, leaving a large and complex body of unfinished writings about the mythology of Middle-earth. His son Christopher Tolkien selected, arranged, edited, and in some places combined material for The Silmarillion, which was published in 1977. The book presents the creation of the world, the history of the Valar and Elves, and the major legends of the First Age.

The Silmarillion is not a conventional novel written in a single finished form. It draws on texts from different periods of Tolkien’s life, and versions of its stories sometimes conflict. Christopher’s editorial work made a coherent published volume possible, but he also explained its editorial history in notes and later publications. The book’s title refers especially to the Silmarils, three extraordinary jewels made by Fëanor and central to the mythology of the First Age.