Monty Python and the Holy Grail

Monty Python's 1975 opus. From Wikipedia:

Monty Python and the Holy Grail is a 1975 British comedy film written and performed by the comedy group Monty Python (Graham Chapman, John Cleese, Terry Gilliam, Eric Idle, Terry Jones and Michael Palin), and directed by Gilliam and Jones. It was conceived during the gap between the third and fourth series of their popular BBC television programme Monty Python's Flying Circus.

In contrast to the group's first film, And Now for Something Completely Different, a compilation of sketches from the first two television series, Holy Grail was composed of new material, and is therefore considered the first "proper" film by the group. It generally parodies the legend of King Arthur's quest to find the Holy Grail. The film was a success on its initial release, and Idle used the film as the inspiration for the 2005 Tony Award-winning musical Spamalot.