US keyboard legend Billy Preston, known for his work with The Beatles and The Rolling Stones as well as his own solo hits, has died at the age of 59.
Billy Preston (left) worked on Beatles albums including Let It Be
Preston played on The Beatles' Let it Be, the Stones' Exile on Main Street and landmark albums by Bob Dylan, Sly & the Family Stone and Aretha Franklin.
He had solo hits in the 1970s with Will It Go Round In Circles, With You I'm Born Again and Nothing From Nothing.
Kidney failure had left him in a coma since November.
Rolling Stones singer Mick Jagger said: "Billy was a fantastic and gifted musician... a superb singer in both recording sessions and on stage.
"He was great fun to be with on stage when touring with us and I will miss him a lot."
Former Beatle Ringo Starr said: "Billy was an incredible musician and an incredible man who will be missed. As Billy said, that's the way God planned it."
Preston also toured and recorded extensively with The Rolling Stones
Born in Houston, Texas, Preston started out playing with Ray Charles and Little Richard.
He became friends with The Beatles when he played with Little Richard in Hamburg and the soon-to-be superstars were the support act.
The musician went on to play keyboards on Let it Be and Abbey Road and the song Get Back was credited to The Beatles and Billy Preston - the only time the Fab Four shared the limelight on a hit single.
"I was at the Beatles' office, and John said, 'Look, Willy' and he showed me the record," Preston told the Chicago Sun-Times two years ago.
"I looked, and it was great. Wow! It was really something to do that for me."
Lennon was even reputed to have suggested that Preston should join the group - but the idea was said to have been scuppered by the rest of the band.
Preston was credited with soothing tensions within The Beatles during the Let It Be sessions - George Harrison likened it to a feuding family staying on its best behaviour in front of a guest.
Preston was a prolific songwriter and enjoyed solo success
And he accompanied the band during their last live show on the roof of the Apple Records building in 1969, which he said was the highlight of his career.
Apple Records managing director Neil Aspinall said he was "truly saddened" to hear the news.
"Billy made memorable contributions to The Beatles' albums Let it Be and Abbey Road as well as recording two solo albums for Apple Records.
"He was a good friend of Apple's and will be greatly missed."
Preston also toured and recorded extensively with The Rolling Stones, playing on classic albums including Sticky Fingers and Exile on Main Street.
His other session credits included Bob Dylan's Blood on the Tracks, Aretha Franklin's Young, Gifted and Black and Sly and the Family Stone's There's a Riot Goin' On.
Solo success grew steadily in the 1970s and he won a Grammy Award for best pop instrumental for his song Outa-Space in 1972.
He shared another Grammy the same year for his part in George Harrison's Concert For Bangla Desh.
A prolific songwriter, he also wrote You Are So Beautiful, a major hit for his friend, British blues singer Joe Cocker.
But his later life was marred by personal troubles. In 1992, he received a suspended jail sentence for cocaine possession and assault charges.
In 1997, he was sentenced to three years in prison for violating the terms of his probation for a drugs possession charge handed out earlier that year.
The musician pleaded guilty to insurance fraud in 1998.
Preston's website said he died in hospital in Scottsdale, Arizona, as a result of "malignant hypertension that resulted in kidney failure and other complications".
His manager Joyce Moore said: "He had been hospitalised for the past several months due to a respiratory arrest and his body just couldn't support him any more."