Record producer Sir George Martin, known as the "fifth Beatle", has died, aged 90.
Breaking the news on Twitter, Beatles drummer Ringo Starr, 75, said: "God bless George Martin peace and love to Judy and his family love Ringo and Barbara George will be missed."
In a career spanning five decades, Sir George signed the Beatles and produced more than 700 records.
He worked with artists including Gerry and the Pacemakers and Shirley Bassey.
God bless George Martin peace and love to Judy and his family love Ringo and Barbara George will be missed xxx ✌️☮— #RingoStarr (@ringostarrmusic) March 9, 2016
A carpenter's son from Holloway in north London, Sir George helped the Beatles achieve global success as the head of the Parlophone record label after hearing their demo tape in 1962.
He took them from their mop-top recordings in the early 1960s to the psychedelia of Sergeant Pepper.
Of his reputation as the "toff" guiding the working-class Beatles to fame, he said: "I've been cast in the role of schoolmaster, the toff, the better-educated, and they've been the urchins that I've shaped.
"It's a load of poppycock, really, because our backgrounds were very similar. Paul and John went to quite good schools. We didn't pay to go to school, my parents were very poor. Again, I wasn't taught music and they weren't, we taught ourselves.
"As for the posh bit, you can't really go through the Royal Navy without getting a little bit posh. You can't be like a rock 'n' roll idiot throwing soup around in the wardroom."
In his lifetime, he won multiple Grammy awards and an Academy Award for the score to A Hard Day's Night.
Martin received a knighthood in 1996 and in 1999, he was inducted into the Rock and Roll Hall of Fame.
BBC Arts editor Will Gompertz described Sir George as "a visionary".
He said: "The Beatles were like an orchestra without a conductor, until the visionary George Martin gave them a shape and a sound. A wonderful man."