I’m going to be slightly pedantic and say that there is no “definitive” source that chronicles all of Arthurian legend effectively… though some do better than others.
One of the real strengths of Arthurian legend – and any good mythology – is that it can be added to and built upon as time passes. All of the examples listed in this thread are excellent ones (Jack Whyte’s series, the Mary Stewart books, and Bradley’s Mists of Avalon are some of my personal favorites), but they are all examples of how the legend has been enhanced by each person who puts energy into it. Whyte puts greater detail into the events leading up to Arthur’s reign, spending a lot of time on the history of a Britain recently abandoned by the Roman occupation and putting aside the magical/mystical elements of the story. In his series, we don’t even really meet Arthur until (I think) the fourth book, and then he is a baby. Mary Stewart’s books flesh out Merlyn’s story in the legend, and include a great deal of magic. Marion Zimmer Bradley focused more on the women in the story – not just Morgaine (Morgan) but Morgause and Guinevere as well – and balanced history and magic nicely.
Even Malory’s version, one of the earliest known incorporating many of the accepted facets of the story, expanded quite a bit on the “original” source material. Steinbeck’s version was essentially a re-writing of Malory, putting it in slightly more modern language and going back to pre-Malory sources. Steinbeck unfortunately never finished it; he died before it was complete, after working on it for many years.
Some of the other “old” sources you might like to look at are Chretien de Troyes’ Arthurian Romances, and the somewhat controversial History of the Kings of Britain by Geoffery of Monmouth. The latter may have been one of Malory’s sources (it pre-dates Malory’s work), but its history is, shall we say, questionable. Still, worth reading if you’re interested.
Anyway, the point is that almost every version of Arthurian legend will add to the story in important ways. Malory’s version is the most “traditional” of them, but it largely focuses on the men in the story and ignores the women. Also, many of the favorite characters (Merlyn, for example) are given somewhat short shrift, which other writers have done excellent work in filling in.
If I may recommend a couple other favorites of mine (I’ve read a great deal of Arthurian legend, both “fiction” and “non-fiction” – the line between them blurs somewhat), Diana Paxson’s Hallowed Isle series, consisting of four relatively short books, is one of the best re-tellings of Arthurian legend attempted by a modern author. Each book takes on the perspective of a different culture in Britain at the time of Arthur’s reign, while the story moves on through them all as the unifying thread. The characters are both familiar and fresh, and the books are a valuable addition to any Arthurian buff’s library. Also, Bernard Cornwell’s three-book Warlord Chronicles (the linked book is the first in the series) is a sharp and original take on the history behind the Arthurian story. Though the story lacks the romance and magic of many of the popular Arthurian works, I get the feeling from other things I’ve read that, if Arthur ever existed, Cornwell’s version, with its unfliching realism, would be a more accurate version of the story than most of the others. I also loved the portrayal of Guinevere in this one; she is a much more complex character than any other version of the story, including some I’ve read which focus on her.
And Caprese has already mentioned my favorite Arthurian scholar (one of the few worth reading, in my opinion), Geoffery Ashe. Almost any of his books are worth having a look at for the historical perspective, with The Discovery of King Arthur being perhaps the best one.
Well, there you have it… a true Arthurian Geek’s perspective, for what it’s worth.
