Which Tolkien work was published posthumously in 1980 from edited Middle-earth materials?

Unfinished Tales was published posthumously in 1980 from edited Middle-earth materials.

The collection was edited by Christopher Tolkien and contains narratives connected with the First Age, Second Age, and Third Age. It includes material about Númenor, the Istari, the children of Húrin, and events surrounding The Lord of the Rings.

The title is literal: these texts were not all complete, polished stories intended for publication in their surviving form. Christopher Tolkien supplied editorial organization and commentary, while preserving different versions and unfinished passages where necessary. This makes the book valuable to readers interested in how Tolkien developed his mythology.

Unfinished Tales is often confused with The Silmarillion, which Christopher Tolkien edited and published in 1977. The Silmarillion presents a more unified account of Tolkien’s mythology; Unfinished Tales is a collection of separate narratives and variants. Later volumes of The History of Middle-earth provided still more drafts and editorial discussion.