Narn I Chîn Húrin; The Tale of the Children of Húrin
While I still love the language and the epic feel that Tolkien creates so beautifully, this book is clearly not as finished or developed as his others. It was left unfinished and his grandson, Christopher Tolkien, finished it based on his grandfather's notes. It goes back before the time of The Lord of the Rings to recount the history leading up to it.
