Neil Innes, the English writer, comedian and musician - dubbed "The Seventh Python" - has died aged 75.
He was best known for his work with the Bonzo Dog Doo-Dah Band, The Rutles and collaborating with Monty Python.
A spokesperson for the Innes family said he had not been suffering from any illness and had passed away unexpectedly on Sunday night.
Innes had been travelling home from France with his family, who have asked for privacy "at this difficult time".
"It is with deep sorrow and great sadness that we have to announce the death of Neil James Innes on 29 December 2019," they said in a statement.
"We have lost a beautiful, kind, gentle soul whose music and songs touched the heart of everyone and whose intellect and search for truth inspired us all.
"He died of natural causes quickly without warning and, I think, without pain."
They went on: "His wife Yvonne and their three sons, Miles, Luke and Barney, and three grandchildren, Max, Issy and Zac, give thanks for his life, for his music and for the joy he gave us all."
The Essex-born star, who was raised in Germany, performed piano, guitar and vocals in The Bonzo Dog Doo-Dah Band - later renamed The Bonzo Dog Band - who had a hit in 1968 with I'm the Urban Spaceman. The track was co-produced by Apollo C. Vermouth - a pseudonym for Sir Paul McCartney.
The comic songwriter penned the track Death Cab For Cutie, which was used in The Beatles' 1967 film Magical Mystery Tour, and later inspired the US band of the same name.
In the 1990s he was given a writing credit on the Oasis track Whatever, after it was found Noel Gallagher had borrowed portions of his song How Sweet To Be An Idiot.
'The Seventh Python'
In the 1970s, Innes became closely associated with British comedy collective Monty Python, contributing sketches and songs like Knights of the Round Table and Brave Sir Robin, as well as appearing in their classic films The Holy Grail and Life of Brian.
He wrote and performed sketches for their final TV series in 1974 after John Cleese temporarily left, and was one of only two non-Pythons to be credited as a writer, alongside The Hitchhiker's Guide to the Galaxy author Douglas Adams.
A film about Innes called The Seventh Python was made in 2008.
After the comedy group came to an end, Innes joined fellow Python's Eric Idle on a new series, Rutland Weekend Television, which gave birth to their spoof band The Rutles - a pastiche of The Beatles.
In the band Innes played Ron Nasty, a character loosely-based on John Lennon.
According to Innes's wife Yvonne, he toured with the Fab Four tribute act The Bootleg Beatles last year.