Le Morte d'Arthur
There are two versions of Le Morte d'Arthur. The first is the edition printed by William Caxton on July 31, 1485; this presents Malory's story as a unified work, divided into twenty-one books. A second version was discovered at Winchester College in 1934, and is thought to be closer to Malory's vision; it is divided into eight separate books.
Le Morte d'Arthur is one of the leading works of medieval Arthurian literature today, and most modern retellings of Arthur's story have drawn directly from it (especially T. H. White's The Once and Future King).