One of the challenges I've faced in compiling this list is that so many of my favorite characters in literature and film aren't fictional at all. William Daniels' John Adams, Peter O'Toole's Henry II, Keith Michell's James Cook, and Kenneth Branagh's Henry V come to mind, along with a host of others. Some of the stories I love best are historical, and so they won't show up here (maybe next year's list will be favorite historic figures). I'm drawing the line at mythic/legendary, so King Arthur makes the cut.
Arthur has obviously been explored many times, in books and on film. Sean Connery's played him in a frothy mess, 1981's Excalibur is a brooding slog, and he's even been a whiny Disney character (one that came closest to T.H. White's Once and Future King classic). Most portrayals insist on Arthur as deadly serious, redolent of gravitas and dignity, a somber, sober man going about a somber, serious business. I think that's why I enjoy Graham Chapman's Arthur so much. He spends the entirety of Monty Python's Holy Grail farce engaged in a straight-faced send-up of the Arthurian sourpuss, and it works on every level.
Arthur, King of the Britons as played by Chapman is utterly convinced of his nobility and rectitude, a conviction undimmed by the self-mocking nature of his transportation, the nuisance of French taunters and Black Knights with detachable limbs, or the prickly challenges of his own over-educated and under-employed filth-farming peasants. Arthur is on a holy quest as ordained by God, and everything else is a minor hurdle. Even rabbits with horrible, pointy teeth, and wise-ass bridge riddlers barely slow him down. He runs away but he keeps coming back, because he is Arthur, and he is your King, and that's all there is to it. He wears his crown like...well, like a crown.
In the end, the only thing that can stop Arthur is the modern police state. The movie itself works on many levels, and I could probably have highlighted many of the memorable characters here: Brave Sir Robin, Tim the Enchanter, Cleese's peril-averse Lancelot, and the rest. But Arthur is the engine that drives it all. Look, there's part of me that enjoys the historic and serious takes on King Arthur, and there are reasons the Camelot mythos resonates with so many of us. But nobody's ever given us an Arthur more kingly and yet more hilarious than Graham Chapman.