''The Book of Merlyn'' is the posthumously published fifth book in T. H. White's retelling of Myth/ArthurianLegend. Written in the 1940s, it remained unpublished due to wartime paper shortage and was not included in the 1958 composite edition of ''Literature/TheOnceAndFutureKing''. The manuscript was finally published in 1977.

Chronologically, it is set ''within'' the fourth book: On the eve of the FinalBattle between KingArthur and Mordred, King Arthur is once more taken by Merlyn to contemplate various things.
!!This work provides examples of:

* AntWar: The Author envisioned this here, but ExecutiveMeddling put it in ''The Sword in the Stone''.
* AuthorTract: On human nature, whether or not it is good by nature, the origins of war and plenty more.
* [[spoiler: FaceDeathWithDignity: Arthur's death -- to the very last, fighting to stem the tide of war and bring peace.]]
* FinalBattle: The evening before it.
* [[spoiler: HopeSpot: Arthur's tranquil experiences as a goose, and his incipient romance with Lyo-lok. Merlyn's timing for yanking him back to humanity is almost cruel.]]
* HumansAreTheRealMonsters: A main point put forward by many of the animals. They even go so far to suggest Homo Sapiens had a more fitting name as Homo Ferox.