Which Tolkien child edited The History of Middle-earth series?

Christopher Tolkien edited The History of Middle-earth series.

Published in twelve volumes between 1983 and 1996, the series presents drafts, revisions, commentary, and related material from J.R.R. Tolkien’s manuscripts. Christopher Tolkien organized the enormous archive and explained how stories, names, languages, and histories changed across successive versions. The books reveal that Tolkien’s legendarium was continually revised rather than written in one fixed form.

Christopher was Tolkien’s third child and worked extensively on his father’s literary estate after Tolkien’s death. He also edited The Silmarillion, Unfinished Tales, and other posthumous publications. The History of Middle-earth is not a single narrative novel and should not be read as a straightforward sequel to The Lord of the Rings. Instead, it is a documentary record of Tolkien’s creative development, including abandoned texts and alternative versions.