In 1970, the Bee Gees did a television special (ala Magical Mystery Tour) which was very reminiscent in comic spirit to Monty Python and the Holy Grail. It featured a number of fine British comedians (Frankie Howerd, Spike Milligan, Eleanor Bron), musicians (Lulu, Eric Clapton, Stevie Winwood), and even Vincent Price.
Like Magical Mystery Tour, it was considered a critical flop - but it's the kind of flop that really grows on you over the years.
Of course it's on YouTube - and of course I'm asking that you go watch it.