''The Once and Future King'' is a retelling by T. H. White of the story of Myth/KingArthur. It is considered one of the best retellings of Arthurian legend. It was originally published as separate books from 1938 to 1941 and collected in one volume in 1958. The 1958 version contains:

# ''[[Main/OriginsEpisode The Sword in the Stone]]'', covering Arthur's childhood, the lessons he was taught by Myth/{{Merl|in}}yn (in which he transforms him into animals in order to give him a different perspective on the world), how he was discovered and crowned King of England.
# ''[[Main/DarkerAndEdgier The Queen of Air and Darkness]]'', covers the early part of Arthur's reign, the founding of the Knights of the Round Table, and introduces Morgause, the mother of Arthur's nemesis Mordred.
# ''[[Main/ADayInTheLimeLight The Ill-Made Knight]]'', focuses on Sir Lancelot as he begins to fall in love with the Queen, while championing Arthur's vision of a better world.
# ''[[Main/GrandFinale The Candle in the Wind]]'', telling of the downfall of Arthur and his kingdom, concluding with a [[BitCharacter bit appearance]] by Creator/ThomasMalory, still a squire, whom Arthur sends off to remember their story.

The first three parts were published separately first, and revised to a greater or lesser extent for the collected edition. The biggest change was probably to the second part, which was substantially altered and given a new title. (The original version had been entitled ''The Witch in the Wood'').

White also worked on a fifth part set before Arthur's final battle, in which he was taught more lessons by Merlyn. Parts of it were incorporated into the collected edition's version of ''The Sword in the Stone''. In 1977, after White's death, it was published separately as ''Literature/TheBookOfMerlyn''.

''The Sword in the Stone'' was loosely adapted into a [[Disney/TheSwordInTheStone Disney film of the same name]]. The musical ''Theatre/{{Camelot}}'' is based on ''The Ill-Made Knight'' and ''The Candle in the Wind''. In 2014, BBC Radio 4 broadcast a six-part adaptation including elements from ''The Book of Merlyn'', adapted by Brian Sibley (who also dramatised ''The Lord of the Rings'' for BBC Radio in the 1980s) and featuring Creator/DavidWarner as Merlyn.
!!''The Once and Future King'' provides examples of the following tropes:

* AbhorrentAdmirer: Elaine of Corbin. After Sir Lancelot saves her, she becomes madly in love with him...despite Lancelot showing no interest in her. She goes so far as to [[spoiler: ''rape'' him by posing as Queen Guenever. And then, later on in the book, [[MoralEventHorizon she does it AGAIN.]]]]
* AbusiveParents: Morgause is a ''horrible'' mother to her children: she abuses them both physically and emotionally, leaving all of her children very very screwed up.
* TheAce: Deconstructed with Sir Galahad, who is so inhumanly ''perfect'' that he is disliked by most of his fellow knights.
* AdaptationalAttractiveness: Inverted with Lancelot. He's generally depicted as handsome in Arthurian legends and almost all adaptations, including the author's source material, but in the book he's emphatically described as having an ugly, "ape-like" face.
* AdaptationDyeJob: Guenever is stated to have jet-black hair, although the narrator admits that in most stories, including the author's source material, she is blond.
* AffectionateNickname: Both Arthur and Lancelot fondly refer to Queen Guenever as "Jenny" ([[AnachronismStew "Jennifer" being the modern English equivalent of "Guenever"]]).
* AllohistoricalAllusion: Crossed with AnachronismStew below; the book doesn't explicitly take place in an alternate universe, but whenever the narrator makes reference to a real-life medieval English monarch, he'll refer to them as "legendary" or "imaginary."
* AnachronismStew: Deliberately set in no particular time period, with historical references being often vague and frequently contradictory. In several cases, White justifies it by saying that some things referenced (such as the characters drinking Port or wanting to send their kids to Eton) weren't ''actually'' what was being said, but that more modern things were used to give readers a sense of what was being said. Of course, this version's Merlyn lives ''backwards'' through time, so he possesses objects and knowledge of the future (a certain madman who caused WWII, for instance, and he keeps guns in his house, as well as dressing in clothes that are unknown to those around him)
* AntWar: One of the animal transformations Merlyn performs on Wart is to turn him into an ant, and he finds himself in the middle of an ant war. Luckily he gets out of it before things turn nasty.
* ApothecaryAlligator: Merlyn has one in his cottage.
-->There was a real corkindrill hanging from the rafters, very life-like and horrible with glass eyes and scaly tail stretched out behind it. When its master came into the room it winked one eye in salutation, although it was stuffed.
* ArgumentOfContradictions: Sir Grummore and King Pellinore have a rather lengthy one following a battle, first about whether Pellinore said "Pax" or "Pax Non," then about whether or not he's a cad, then a bit later about him being a cheat. The whole thing continues on and off for about a page.
* AuthorityInNameOnly: ''King'' Pellinore doesn't actually have a kingdom to rule over, instead he acts like any other knight chasing the Questing Beast.
* BadassCreed: The song of the hawks in ''The Sword in the Stone''.
* BastardBastard: Sir Mordred. Boy, oh, boy. Sir Mordred.
* BawdySong: One is mentioned in passing about a king and a fair maiden; in the first verse, which is given in the text, the king sees the maiden's ankle as she steps over a puddle, and in subsequent verses, which are left to the reader's imagination, he gets to see more.
* BeautyEqualsGoodness: Averted with Lancelot.
* BiggerBad: Morgause is only seen in the second book, but it's her actions that only fuel between the Orkney Clan and the Pendragons
* BiTheWay[=/=]IfItsYouItsOkay: Lancelot was in love with Arthur, though one might argue what "in love" specifically means. His jealousy and hostility towards Guenever actually plays a part in them ending up together.
* BittersweetEnding: [[spoiler: The Round Table is no more. Arthur can never see Lance or Guenever ever again. All his attempts of forcing might to be used for right have failed, and he will die in his final battle to be killed by his own son, Mordred. However Arthur takes comfort in the fact that young Tom will keep the legend and ideals of King Arthur alive for centuries to come.]]
* BookEnds: The 4th book ends with Arthur reminiscing about his lessons with Merlyn as Wart- specifically, the difference between the pacifist geese he flew with, and the militaristic ant colony.
* BringNewsBack: [[spoiler:Why Thomas Malory can not fight and die in the last battle as he tells Arthur he wants to.]]
* BrokenAce: Lancelot becomes so obsessed with becoming the greatest knight in the world that he gives his entire childhood in the pursuit of this dream. Throughout the book, he is shown to be extremely uncomfortable in his own mind, and is quite self-loathing.
* CallOfTheWildBlueYonder: In the first part Arthur expresses to Merlin a wish to fly, so Merlin turns him into a bird of prey (a [[http://en.wikipedia.org/wiki/Merlin_(bird) merlin]], naturally), and puts him in with the castle's hunting falcons.
* CanonForeigner: Madam Mim from ''The Sword in the Stone''. Though she was cut from the revised 1958 omnibus edition, she was restored for the Disney movie.
* TheCatfish: In ''The Sword in the Stone'', the big old fish lurking in the moat of Sir Ector's castle.
* CelibateHero: Required if you want to reach the Holy Grail. Thus, Sir Galahad, Sir Percival and Sir Bors (though he has had sex once, it is forgiven for it was for the sole purpose of bearing a child).
* CerebusSyndrome[=/=]DarkerAndEdgier: ''The Sword and the Stone'' is pretty light-hearted, and not much different than the Disney film in terms of atmosphere. The story darkens from the second book onwards- we first get a [[spoiler:description of how Morgause boils a cat alive just for the lulz]]. White also intended the books to be poetic, comedic, dramatic and tragic in order.
* ChasteHero: Lancelot...until he meets Guenever.
* ContinuityNod: The narrator flatout brings up ''[[Literature/LeMorteDarthur Le Morte d'Arthur]]'' in reference to several of the book's events but [[Main/AdaptationExpansion also expands on characterization and story]].
* CycleOfRevenge: Between the Orkney Clan and the Pendragons due to what Uther did to Igraine.
* DeusAngstMachina: ''Everything'' that happens to Lancelot and much of what happens to Guenever. In the concluding book Arthur, Guenever and the Orkney brothers (excepting Mordred) all go through hell.
%% * EndOfAnAge
* EternalHero: Lampshaded and parodied in ''The Candle in the Wind'', where Merlin (who was born an old man at the end of the universe and lives his life backwards in time to an eventual death as a baby during the Big Bang) devotes a couple of paragraphs to [[LeaningOnTheFourthWall confusing Arthur by criticizing future retellings of his legend]], [[GenreSavvy mercilessly savaging White's version ("Imagine, beginning with the Normans and ending with the Wars of the Roses")]] for using ComicBookTime to allow Arthur and the others to [[MindScrew live through centuries of history while simultaneously only living for normal human lifespans.]]
** This scene starts with the duo meeting a young boy [[NoFourthWall who turns out to be called]] [[spoiler:Thomas Malory]]...
* EvilCounterpart: The drunken, lazy St. Toirdelbach is to the Orkney boys what Merlyn is to Arthur.
%% * {{Excalibur}}
* TheFairFolk: [[OlderThanTheyThink Before Gaiman]] did this, the fairies in ''The Sword in the Stone'' were one of the earliest examples of these in modern fiction. Robin Wood said that they didn't have hearts, both literally and figuratively.
* FamedInStory: Arthur wanted the story told, at the end, to keep the memory of the ideals alive.
* FeudingFamilies: The Orkney Clan and the Pendragons, due to what happened between Uther and Igraine. Mainly one-sided as the only Pendragon left is Arthur and he wants nothing more than to make peace with the Orkney Clan and be friends.
* FoodChains: Subverted in Arthur's and Kay's faerie sojourn, where they're not in the least tempted by any of the food they encounter because it's awful.
-->It was horrible beyond belief--sweet, sickly, and pungent--so that they did not feel the least wish to swallow a particle of it. The real temptation was to run away.
* ForgottenFallenFriend: In the fourth book, Lancelot kills [[spoiler: Gawaine's brothers Gareth and Gaheris. Though Gareth's death is devastating to both Gawaine and Lancelot, neither of them seems to remember that Gaheris ever existed. (Or any of the brother's wives, who reportedly exist, but ever appear in the book.) Sir Kay's death goes pretty much unnoticed as well. (Unless White means a different Sir Kay.)]]
* ForTheEvulz: the "motivation" of Mordred, Morgaine, Morgause (all related) and many walk-on villains.
* FreudianExcuse: Agravaine and Mordred, much more literally than usual.
* GoodIsNotNice: Sir Galahad is detested by most of the knights he comes into contact with, because he is far too good to be merely polite.
%% * TheGoodKing: Arthur
* {{Gorn}}: Queen Morgause [[spoiler:boils a cat alive]] out of boredom. She doesn't even care about the practical purpose of granting invisibility, as she's intensely vain.
** This is also a highly effective [[KickTheDog Kicking of the Dog]], since the second book (and her first scene) ''opens'' with her doing this.
* HappilyMarried: Igraine and Cornwall. Until Uther comes along and decides that he [[ItMustBeMine would like to have Igraine for his wife, instead]].
* HotWitch: Queen Morgause is described as a "black-haired, blue-eyed beauty". She ends up sleeping with Arthur and setting in motion his eventual downfall.
* IndividualityIsIllegal: The ants Arthur meets in one of Merlyn's lessons. "EVERYTHING NOT FORBIDDEN IS COMPULSORY." White flat-out states that the ants are Communists.
* {{Jerkass}}: From what we hear, Uther is not a very nice person. He's a reliable king, but he follows the old "Might ''is'' Right" mentality. That and what he did to claim Igraine as his wife, even though she was already marrried to Cornwall.
* JerkWithAHeartOfGold: Sir Kay, even as a little boy. It's somewhat understandable, seeing as he grew up under a wealthy lord and was spoiled. However after getting over the initial shock of having his younger foster brother becoming King of England, he's very loyal and devoted to his brother.
* JustSoStory: The badger's dissertation in ''The Sword in the Stone'' is a just-so story about how the animals got their various wings, claws, fins, etc.
* KavorkaMan: Sir Lancelot. He is known as ''Le Chevalier Mal Fet'', "the Ill-Made Knight", as he is short, ugly and quite possibly ridiculously bow-legged. Yet he is loved by Guenever and Elaine, and admired by many other ladies as well.
* LampshadeHanging: Merlyn does this ''constantly'', since he's basically GenreSavvy due to moving backwards through time. Some of his most marvelous ones spiral off into funny and inspiring sermons about learning and the nature of spoken language.
* LevelAte: In ''The Sword in the Stone'', Arthur and Kay enter a faerie castle made of food. Said food turns out to be lakes of butter, walls of cheese, and the Fairy queen is found on a bed of ''lard''.
--> ''Narrator:'' It was horrible beyond belief-sweet, sickly, and pungent- so that they did not feel the least wish to swallow a particle of it. The real temptation was to run away.
* LoveTriangle: Arthur/Guenever/Lancelot, of course, although it doesn't fit any of the traditional TriangRelations as it's made very clear several times that while Gwen and Lance are very much into one another, they both love Arthur too (and he explicitly says that he loves them both dearly as well).
** LoveDodecahedron: It's not just Arthur/Guenever/Lancelot, it's explicitly Arthur/Guenever/Lancelot/''God'', with occasional complications from Elaine and Morgause.
* MerlinSickness: Trope namer and codifier. Merlin was/will be born in the future, and ages backwards through time. He remembers the future, and frequently gets confused as to what has and what has not happened yet.
* MightMakesRight: A central discussion within the book. Arthur strives to leave behind the old school's ideas of "Might Is Right" and redirect it as "Might for Right", adapting Might as a force for good.
-->'''Lancelot''': The man with the strongest arm in a clan gets made the head of it, and does what he pleases. That is why why call it Fort Mayne. You want to put an end to the Strong Arm, by having a band of knights who believe in justice rather than strength. Yes, I would like to be one of those very much.
* MisterMuffykins: Mordred's mother, Queen Morgause, has a succession of these little lapdogs. Mordred grows up hating them, but as an increasingly unstable adult starts keeping his own.
* MoodWhiplash: ''The Queen of Air and Darkness'' switches from the lighthearted romps of the comical King Pellinore and the darker scenes featuring Queen Morgause.
* {{Motifs}}: Several, one early one being the crow with an arrow in its beak, which symbolizes trouble to come. It's first seen catching the Wart's arrow, upon which Kay claims it was a witch's doing. The same crow is seen at Morgan le Fay's castle, and then a crow-with-arrow weathervane sits atop the Orkney castle.
* NakedFirstImpression: When Lancelot goes to save Elaine from the cauldron of boiling water she's been magically imprisoned in for years, she is "naked as a needle."
* ANaziByAnyOtherName: The Thrashers of Mordred.
* OedipusComplex: [[Main/WellDoneSonGuy All of the Orkney boys suffer from desperately wanting to please their]] [[EvilMatriarch mother, Morgause]]. But it's heavily implied that only Mordred and Aggravaine are sexually attracted to her. [[spoiler: [[{{Matricide}} To the point where they end up murdering her. Yikes.]]]]
* OneSteveLimit: Averted. The narrator even goes as far as to point out to the reader how the Elaine of Corbin (who is in love with Lancelot) is not the same as Queen Elaine, sister to Queen Morgause and Morgan le Fey.
** Same with Sir Bors and his son...who is also referred to as Sir Bors.
** And then there's Sir Ector, who was Arthur's childhood guardian and Sir Ector De Maris, who is cousins with Sir Bors and Sir Lionel.
* OnlyTheChosenMayWield: The eponymous sword of ''The Sword in the Stone'', which can only be freed from the stone by he who is "rightwise king born of all England".
* PatrickStewartSpeech: ''The Book of Merlyn'' contains a lengthy HannibalLecture on humanity's flaws, which seems like a massive downer. However, it does follow it up with a brief PatrickStewartSpeech on what the speaker considers to be humanity's saving grace: the love it has for its pets.
* PetsHomageName: Merlin's {{Familiar}} is an owl named Archimedes, after the ancient Greek mathematician. And you may NOT call him "Archie".
* PoliticallyIncorrectHero: Sir Bors the younger. The book is quick to frequently call him out as a misogynist...but he's also one of the three knights that achieved the Holy Grail. Not to mention how he's fiercely loyal to Lancelot and agreed to be the Queen's champion when Lancelot wasn't around even though it's been made ''very'' clear he can't stand her.
* PreAssKickingOneLiner: Lancelot has one in Candle in the Wind, before he goes out to fight the knights who are confronting him about his affair with Guenever:
-->"Ah sirs," he said with a grimness, "is there none other grace with you? Then keep yourselves."
* PublicDomainCharacter: Apart from the obvious, Arthur meets RobinHood (who says his name is really Robin ''Wood'', but it's clearly the same person the legends are about) in ''The Sword in the Stone''. Several personages from Greco-Roman mythology, such as Neptune, Hecate, and Minerva, also make appearances in ''The Sword in the Stone'' (not to mention Castor and Pollux blowing Merlyn to Bermuda).
* RedRightHand: The description of Mordred's appearance makes it clear he's not to be trusted:
-->He was a thin wisp of a fellow, so fair-haired that he was almost an albino: and his bright eyes were so blue, so palely azure in their faded depths, that you could not see into them. He was clean-shaven. It seemed that there was no part of him which you could catch hold of, neither his hair, nor his eyes, nor his whiskers. Even the colour had been washed out of him, it seemed, so as to leave no handle. [...] He walked with an upright carriage, both ingratiating and defiant -- but one shoulder was higher than the other. He had been born slightly crooked -- a clumsy delivery by the midwife -- like Theatre/RichardIII.
* ReferenceOverdosed: It's packed with historical and literary allusions (mostly medieval, but with plenty of Shakespeare and others thrown into the mix).
* RevengeByProxy: Since Uther killed the Duke of Cornwall to have Igraine as his wife, Morgause and children forever resent and plot against Arthur even though he really nothing to do with it.
* SacrificedBasicSkillForAwesomeTraining: Lancelot devoted most of his youth to learning how to fight, at the expense of having a proper childhood. He's better with a weapon than anyone else in the book, but among other things, he never learned to climb trees.
* SpellMyNameWithAnS: Most notably "Merlyn" (with one discrepancy in the poem before Book 1, where the name is "Merlin") and "Guenever" (in lieu of "Guinevere" or any other varied spelling).
* SpinningOutOfHere: Merlin always spins around before he disappears in a cloud of smoke.
* SupportingProtagonist: King Arthur is clearly the protagonist until the ''[[Main/ADayInTheLimeLight Ill-Made Knight ]]'', where Lancelot takes over as the protagonist. In the final section, we switch between the two perspectives before settling on King Arthur to wrap things up.
* TearfulSmile: After Lancelot and Guinever quarrel and make up:
-->The Queen dried her tears and then looked at him, smiling like a spring shower.
* TookALevelInBadass: King Pellinore, first introduced as a friendly but bumbling knight, becomes a formidable jouster after his marriage to Piggy.
* TheTourney: Unusually, using the melee form.
* TranslationConvention: Explicitly invoked by the narrator. In the first few pages the narration states that characters are actually using or referring to certain period-accurate things like some kind of drink, but the narration will translate it into a modern equivalent, like port. In addition, most of the dialogue is in modern colloquial English, but for a few important parts here and there it switches to something much more old-fashioned-sounding. There is no in-universe explanation for this; the switch is probably just to drive home the point "this is important".
* VirginPower: Invoked by Lancelot, believing this is the case early on in the Ill-Made Knight.
* WhiteHairBlackHeart: Mordred is "so fair haired that he was almost an albino." He is, at first, merely self-pitying and creepy in the give-the-poor-kid-a-break way, but ultimately turns evil.
!! The BBC's 2014 radio dramaitzation of ''The Once and Future King'' provides examples of the following tropes:
* AdaptationDistillation: The serial starts out with Arthur in his tent waiting for the final battle against Mordred, when Merlyn comes into his tent "taking a leave of absence" from Nimueh's cave, a scene take from The Book of Merlyn. Rather than go to the Badger's sett they reminsce about Arthur's childhood and how they met, leading to the events found in ''The Sword in the Stone'', and continuing from there.
** The comic subplot involving King Pellinore from ''The Queen of Air and Darkness'' is left out, making it a very grim episode.
* AdaptedOut: The episode with the hawks is left out, as is the adventure with Robin Hood. The royal boar hunt if also left out, although it's aluded to. The Hedgehog whom Wart meets before he sees Badger is also left out.
* AnachronicOrder: Although the serial follows the general order of White's novel but there are some scenes appear out of order, due to the FramingDevice of Arthur and Merlyn looking back on events before the final battle with Mordred.
* CanonImmigrant: Madame Mim, the witch from ''The Sword in the Stone'' who was cut from the 1958 omnibus edition including all four books, is restored here. Although as a flashback during the episode covering ''The Queen of Air and Darkness'' instead of the episodes covering ''The Sword in the Stone''. It's justified as Merlyn uses it to show Arthur how being sneaky in battle can be justified.
* DemotedToExtra: King Pellinore is mostly a minor character.
* GenderFlip: The Badger becomes a female.
* TakeThat: Merlyn is reading ''Literature/AConnecticutYankeeInKingArthursCourt'' during Kay's jousting practice and calls it "insufferable twaddle".