The most famous of all medieval versions of the chivalric adventures of King Arthur is Thomas Malory’s Le Morte d’Arthur. There is some conjecture as to whether Malory was author or compiler of the stories but his arrangement is the one usually accepted as the definitive Arthurian romance and the one that has most influenced subsequent literature and Hollywood film.  
Sir Thomas Malory is generally believed to be a native of Newbold Revel in Warwickshire.
He was probably born sometime around 1405 and died in March of 1471, less than two years after completing Le Morte d’Arthur.
Malory is one of the most colourful authors in this The Great Books List. Twice elected to Parliament, Malory was also a criminal of note with charges of burglary, rape and sheep stealing leveled against him. He managed to parlay his position as a favourite of both King Henry VI to initially evade conviction. But Henry’s successor Edward IV specifically excluded Malory from any royal pardons. He was imprisoned on more than one occasion and twice escaped, once quite violently. Malory noted in his manuscript that at least some of Le Morte d’Arthur was written in prison.  
Le Morte d’Arthur is a compilation and reinterpretation of a number of older English, Welsh and French chivalric romances. The book also contains original stories, such as the Tale of Sir Gareth. While the book contains many of the trappings of courtly love, magic and a blend of pagan and Christian motifs the book was also written during the closing years of the Wars of the Roses and a number of the book’s events concern political turmoil, questions of royal succession, bloodshed and power grabs, fratricide and civil war.  
Originally titled The hoole booke of kyng Arthur & of his noble knyghtes of the rounde table. The book was first published in 1485 by William Caxton who renamed it  Le Morte Darthur. In 1932, an original manuscript was discovered in Winchester and it was apparent that Malory’s intention was to publish a number of separate tales and that Caxton had edited and compiled the books into one volume.
The book was initially very popular and was reprinted several times up until the English Civil War in the 1660s. The book slipped from favour after the war and sank into obscurity until the Romantic Revival in the early 19th Century.

Le Morte d’Arthur

The book relates eight Arthurian legends that, for the most part, make up the narrative most modern readers are familiar with. The first book tells the story of Arthur’s parents Igraine and Uther Pendragon, his youth and education at the hands of the magician Merlin. England is in turmoil and under the heel of invaders and barbarians. Arthur fulfils an ancient prophesy by pulling the sword Excalibur from a stone and he is proclaimed King of England and begins to consolidate his kingdom through a series of battles.
The first book also introduces the characters of Arthur’s half sister Morgan and her son Modred, duplicity fathered by Arthur. The first book also details Arthur’s marriage to Guinevere and his inheritance of her father’s round table. The book ends with Arthur gathering nobles to his castle and forming the Round Table company of knights.
Book Two is based on Geoffrey of Monmouth's Historia Regum Britanniae and relates the story of Arthur’s war on Lucius the Emperor of Rome.
Arthur’s England is at peace and Sir Lancelot and Sir Tristan have arrived at Camelot. Various knightly adventures are related but them envoys of the Roman Emperor arrive and demand tribute. Arthur decides to wage war on the Romans and takes his army to France. There, in order to encourage his men he decides to take on a giant who has terrorized Normandy. In the shadow of Mont St. Michel Arthur battles the giant finally vanquishing him. Arthur then leads his men against Lucius and defeats the Romans.
"The Noble Tale of Sir Lancelot Du Lake" is the third story and relates the adventures of Arthur’s most trusted and favourite knight. The book details how Lancelot claims everything he does is for Guinevere and this is extolled as the apex of courtly love, however the hint of adultery begins to undermine Arthur’s authority. One adventure also sees Lancelot enchanted by Morgan La Fey before he escapes her clutches, but it marks the point where Morgan’s power eclipses Merlin’s.
Book Four relates the tale of Sir Gareth  and his lusty conquests and battling adventures against the Black, Green, Red, and Blue knights and the Red knight of the Red Lands, while Book five relates the Story of Sir Tristam especially the famous story of his relationship with Isolde. Both Gareth and Tristan are significantly un chivalrous --  often opportunistic, violent and adulterous. These books seem to indicate a change in the moral virtues of Camelot and foreshadow the events in the remainder of the book.
Book six relates perhaps the most famous Arthurian legend --  the quest for the Holy Grail. Based on the French La Queste Del Saint Graal, Malory’s version tells the story of the Knights of Camelot and their individual quests to find the Grail after it appears to them in Camelot. Lancelot, Percival, Bors, and Galahad also decide to undergo the quest.
Most of the knights fail although Galahad, Percival and Bors succeed only to have Galahad vanish with the Grail.

The last two books portray the fall of Camelot and death of Arthur. In "Sir Launcelot and Queen Gwenyvere,” the relationship between the knight and Queen becomes adulterous.
In "The Death of Arthur" Mordred and his brother Agravaine uncover Lancelot and Guinevere's adultery and they out the lovers. Lancelot kills Agravaine and escapes. But Guinevere remains and a broken Arthur sentences her to burn at the stake. Gawain, Mordred, Gareth, and Gaheris, are ordered to guard the Queen knowing that Lancelot will attempt a rescue. Gawain refuses, but the others follow Arthur’s orders. When the inevitable raid comes, many knights are killed including Gareth and Gaheris. Gawain, vows revenge on Lancelot and prompts Arthur to track down Lancelot. Arthur pursues Lancelot to his home in France to continue the fight. Gawain challenges Lancelot to a duel, but loses. Lancelot refuses to kill Gawain and grants him mercy. But before Arthur can challenge Lancelot he receives a message that Mordred has usurped his throne. Arthur leads his army to recapture his thrown. Gawain is mortally wounded but writes to Lancelot forgiving him for his transgressions and begging him to return and aide Arthur. But Arthur is forced to battle Mordred at the Battle of Salisbury. Mordred and Arthur finally meet on the battlefield and Arthur impales his son. But Mordred strikes Arthur with a mortal blow. As he is dying, Arthur sends Sir Bedivere to cast Excalibur into the lake, where it is retrieved by the hand of the Lady of the Lake.
Arthur is carried by barge to Avalon where he is buried. Lancelot returns too late and travels to see Guinevere who has now become a nun. Lancelot takes a vow to become a monk. Arthur's successor is appointed, but England is no longer the same.