Which Tolkien family member edited The Silmarillion for publication?

Christopher Tolkien edited The Silmarillion for publication.

The Silmarillion was published in 1977, four years after J.R.R. Tolkien’s death. Christopher Tolkien worked from a large and complicated body of writings left by his father, including multiple versions of stories, notes, and unfinished passages. He organized and edited these materials into a publishable volume.

The book presents the creation of the world and the history of the First Age, including the Valar, the Silmarils, the rebellion of the Ñoldor, and the wars against Morgoth. It is more mythic and compressed in style than The Hobbit or The Lord of the Rings.

Christopher’s editorial role does not mean that every sentence was drafted as a finished book by J.R.R. Tolkien. The final volume necessarily involved selection, arrangement, and editorial decisions. Christopher later documented much more of that process in The History of Middle-earth.