British comedy troupe Monty Python's second feature film, Monty Python and the Holy Grail (released in 1975) is unlike most Python products in that the entire film, however nonsensical it becomes at times, is all part of a single story rather than merely a series of skits without much, if any, relation to each other aside from the actors involved. And who are those actors? Well, according to the Internet Movie Database1...
Graham Chapman played King Arthur, the voice of God, the middle head of the three-headed knight, and the hiccupping guard of Prince Herbert.
John Cleese played the second soldier interested in the migratory habits of swallows, the man with a supposedly dead body, the black knight, the peasant who claims he was turned into a newt, the incredibly rude Frenchman, Tim the Enchanter, and Sir Launcelot the Brave.
Eric Idle played the collector of dead bodies, one of the peasants insistent on the burning of the supposed witch, Sir Robin the Not-Quite-So-Brave-as-Sir Launcelot, the confused guard of Prince Herbert (the one that doesn't hiccup), Sir Launcelot's trusty steed Concorde, Roger the Shrubber, and Brother Maynard.
Terry Gilliam played King Arthur's trusty steed Patsy, the Green Knight, the soothsayer/bridgekeeper, Sir Gawain, and is responsible for the animation.
Terry Jones played the old woman in the mud with Dennis (see Michael Palin's roles below for information on who that is), Sir Bedevere, the left head of the three-headed knight, the voice of the cartoon scribe, and Prince Herbert.
Michael Palin played the first soldier interested in the migratory habits of swallows, Dennis (the peasant who speaks of being repressed by the monarchy), the peasant carpenter at the rally to burn the witch, the right head of the three-headed knight, Sir Galahad the Pure, the head of the Knights Who Say Ni!, the narrator, the king of the swamp castle, and Brother Maynard's roommate.
All the Monty Python members contributed to writing the script and the film was directed by Terry Gilliam and Terry Jones. Monty Python members weren't the only ones in the film but certainly no one else played as many roles as they did. Random bit of trivia: Author Iain Banks, working as an extra, appeared as a part of King Arthur's army at the end.
The plot of Monty Python and the Holy Grail, if you couldn't figure it out from the title or some of the character names, is a spoof of the legend of King Arthur and the Knights of the Round Table and their quest to find the Holy Grail, the holy chalice of Christ used during the Last Supper. With all of Monty Python's renowned silliness and a somewhat cohesive storyline, Monty Python and the Holy Grail has achieved a somewhat legendary status among comedies and probably has the most well-known script amongst Python fan(atic)s. Even a casual fan could probably recite a few lines from this flick.2 The film's props and feel are somewhat low-tech, due to the troupe's severe lack of funds for the film. Fortunately, Monty Python makes it work, even without a big budget (Led Zeppelin actually helped out with the film's budget at some point).
This movie is great if you like really silly things. If you're more concerned with things making sense and whatnot, even in comedy, you may not like this. The movie contains a song about Camelot, men following King Arthur and his knights clapping together coconuts in the place of horses, a castle full of virgins "all between sixteen and nineteen and a half" found by Sir Galahad the Pure, some of Terry Gilliam's trademark animation, the Holy Hand Grenade of Antioch, a completely ridiculous ending (followed by some silly intermission-esque organ music on a blank black screen for a few minutes... for no real reason), and plenty of other hilarity. Some of Python's best. The film obviously had a very low budget but I feel this only adds to the fun.
Running time: About 90 minutes. Currently available on DVD in a special edition with a commentary track from all the members of Monty Python (except the late Graham Chapman) and a few other behind-the-scenes type things. There's a DVD and VHS version without all this special stuff that was out before the special edition one as well. Distributed by Columbia Pictures.
1This is not just a copy and paste from IMDb.
2I'm not including any huge collection of samplings of dialogue in this node because transcriptions and audio samples can be easily found throughout the web in a ton of places. Some of them are undoubtedly noded at the time of this writing as well.
Thank you, CloudStrife, for some bits of information.