Sir George Martin, the record producer known as the Fifth Beatle, has died peacefully at his home, his manager has confirmed.
The 90-year-old helped The Beatles achieve global success as the head of the Parlophone record label after hearing their demo tape in 1962.
His manager Adam Sharp paid tribute to him as "a true gentleman to the end".
In a statement Mr Sharp said: "The family would like to thank everyone for their thoughts, prayers and messages of support.
"In a career that spanned seven decades he was an inspiration to many and is recognised globally as one of music's most creative talents. He was a true gentleman to the end.
"The family ask that their privacy be respected at this time."
Ringo Starr paid tribute to Sir George for his "love and kindness" to the Fab Four through the years.
He tweeted: "God bless George Martin peace and love to Judy and his family love Ringo and Barbara. George will be missed."
He captioned a picture of the Fab Four and Sir George with the phrase: "Thank you for all your love and kindness George peace and love."
Sean Ono Lennon, son of John and Yoko, posted a picture of Sir George on Instagram with the caption: "R.I.P. George Martin. I'm so gutted I don't have many words. Thinking of Judy and Giles and family. Love Always, Sean."
Prime Minister David Cameron tweeted: "Sir George Martin was a giant of music - working with the Fab Four to create the world's most enduring pop music."
Sir George studied at Guildhall School of Music and played the oboe professionally in London before joining the recording industry.
During his career, which spanned seven decades, he was awarded two Ivor Novello awards, six Grammys and in 2008 was the recipient of the Grammy Foundation's Leadership Award.
In 1965 he was nominated for an Academy Award for his work on the music in A Hard Day's Night and in 1984 he received the Brit award for outstanding contribution to music, having been named best British producer at the first Brit awards in 1977.
In 2012, the BBC filmed a documentary about his life, Produced By George Martin.
Up until his death, he continued to write music, work with charities and advise broadcasters, according to the website for the independent music publisher he set up in 1969.
His son Giles is also a producer who has worked at Abbey Road studios, where Sir George helped the Beatles perform the world's first live global broadcast.