Which character edited and published Tolkien's unfinished work The Silmarillion after his death?

Christopher Tolkien edited and published The Silmarillion after his father's death.

The book appeared in 1977, four years after J.R.R. Tolkien died. It presents the creation of Eä, the history of the Valar and Elves, and the long struggles against Morgoth, the first Dark Lord. Much of this material had been developed and revised across Tolkien's lifetime.

Christopher faced a difficult editorial task because the surviving manuscripts contained different versions, incomplete passages, variant names, and changes in chronology. He organized the material into a coherent posthumous volume, while acknowledging that some decisions necessarily involved selection and arrangement.

The Silmarillion is not a conventional sequel to The Lord of the Rings. It is closer to a collection of mythology and legend, with stories such as those of Beren and Lúthien, Túrin Turambar, and the fall of Númenor. Christopher later published more of the underlying drafts in The History of Middle-earth.