Pop superstar George Michael's death from suspected heart failure has prompted an outpouring of shock and sadness from celebrity friends and fans.
Big names from the world of entertainment paid tribute after hearing about his death, which comes in a year that has seen the music industry lose some of its most well-known stars including Prince, David Bowie and Leonard Cohen.
Sir Elton John posted a photograph of himself and Michael on Instagram, writing: "I am in deep shock. I have lost a beloved friend - the kindest, most generous soul and a brilliant artist. My heart goes out to his family and all of his fans."
Michael's former Wham! bandmate Andrew Ridgeley said he was "heartbroken at the loss of my beloved friend Yog", an affectionate nickname used for the star.
He said: "Me, his loved ones, his friends, the world of music, the world at large. 4ever loved. A xx"
Friend Madonna paid her own tribute, posting an undated video on Twitter in which she embraced Michael on stage. In it she tells the audience: "He's a great songwriter and he makes very classy videos, like me."
Referencing several of his best known lyrics, she adds: "George, I want your sex, so be my father figure and I will have faith if we have to live hand-to-mouth. The diva himself."
Michael formed Wham! with Ridgeley in 1981, and went on to achieve massive success, releasing a string of hit singles including Wham Rap! (Enjoy What You Do), Club Tropicana, Wake Me Up Before You Go Go, and Last Christmas.
They were the first Western pop act to visit China when they played there in 1985, before splitting in 1986, by which time Michael had already released a handful of solo singles.
Fans and neighbours gathered at his homes in Highgate, north London and Goring-on-Thames in Oxfordshire to pay tribute to an artist they described as a "huge inspiration".
People visited to lay flowers, light candles and recalled memories of listening to his music, seeing him live or meeting him.
Spandau Ballet star Martin Kemp and his wife Shirlie - a backing singer for Wham! with her musical partner Helen "Pepsi" DeMacque as part of the act Pepsi & Shirlie - have both paid tribute to Michael.
Kemp wrote on Twitter: "My whole family and I are devastated at the loss of our beautiful friend Yog! We will miss him so much! We are all heartbroken!"
Shirlie wrote that she is "beyond heartbroken".
She added: "Words cannot express how sad we all are, only last week I saw him laughing and happy. My heart is broken to lose someone so special."
Martin Fry, lead singer and songwriter with Look Of Love band ABC, said on Twitter: "Absolutely devastated to hear of the loss of @GeorgeMichael Truly brilliant talent #sad #sad #sad."
Queen's Brian May, who worked with Michael in the 1990s, wrote a tribute on his official website, condemning the year for "cruelly" taking so many "fine people way too young". Holly Johnson, lead singer of Frankie Goes To Hollywood, said: "Sad to hear the news about George Michael , and so many great singers and songwriters we lost this year."
Sir Paul McCartney, who worked with Michael on the 2006 release Heal The Pain, also paid tribute. He said: "George Michael's sweet soul music will live on even after his sudden death. Having worked with him on a number of occasions his great talent always shone through and his self deprecating sense of humour made the experience even more pleasurable."
And 1980s pop star Howard Jones, known for the song I'd Like To Get To Know You Well, said: "Can't believe George Michael has passed ....one of the greatest singers and writers the UK ever produced. I'm really saddened ..a lovely man."
Alison Moyet, who performed at Live Aid in 1985 on the same bill as Michael, said: "I met George Michael a few times & he was ever a gentle, unassuming soul. A rare presence in a world full of self. Honest, genuine talent."
The star kept many of his good works secret as he was "determined not to make his generosity public", according to Childline founder and president Dame Esther Rantzen.
She revealed that Michael had given the royalties from his 1996 number one single Jesus To A Child to the charity.
She said: "For years now he has been the most extraordinarily generous philanthropist, giving money to Childline, but he was determined not to make his generosity public."
Hours after his death it was revealed he had given £15,000 to a gameshow contestant who spoke of needing funds for IVF treatment, and worked anonymously at a homeless shelter.