Sir Elton John has led the tributes to his "beloved friend" George Michael, who died on Christmas Day aged 53.
The Rocket Man singer said he was "in deep shock" at Michael's death.
The pair famously collaborated on a rendition of Elton's classic Don't Let The Sun Go Down On Me, released in 1992, nearly two decades after the original.
Writing on Instagram, Elton said: "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."
Pop stars from the former Wham! front man's heyday were joined by current chart-toppers in declaring their sadness.
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."
Contemporaries Duran Duran referenced the so-called "curse of 2016" - which has seen the deaths of rock and pop behemoths David Bowie, Prince and Rick Parfitt, posted on their official Twitter account: "2016 - loss of another talented soul. All our love and sympathy to @GeorgeMichael's family."
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."
This year's X Factor winner Matt Terry said: "Noooooooooooooooo! I cannot believe this !!!! RIP George Michael".
Former Radio One disc jockey Tony Blackburn said: "Unbelievable, George Michael has died at the age of 53. RIP.This dreadful year goes on and on.So sad, a real talent."
One-time X Factor winner Shayne Ward said: "Absolutely shocked to hear that one of my vocal idols @GeorgeMichael Has passed away. I adored his voice."
Producer and musician Mark Ronson said: "I bought (& worshipped) Listen Without Prejudice on my 15th birthday. This song readied me for Stevie Wonder... Other than a global pop phenom, George Michael was one of the true British soul greats. A lot of us owe him an unpayable debt. bye George xx"
Singer and stage actress Pixie Lott said: "Grew up listening to the beautiful and talented @GeorgeMichael - my mama's favourite! was a pleasure to meet him so sad to hear the news."
Fellow pop star La Roux said: "Another one gone.... What a voice, what a songwriter."
Matt Lucas, who worked with the singer during a sketch for BBC comedy Little Britain, said: "Well 2016, you had to just take one more, didn't you?"
His Little-Britain co-star David Walliams said: "I pray George Michael finally finds peace. A deeply private man with an awe-inspiring talent that couldn't help but make him a superstar."
Mayor of London Sadiq Khan said: "Very sad to hear the news about George Michael. An incredible talent who brought joy to millions of us with his music."
Fellow politician Nicola Sturgeon, the First Minister of Scotland, said: "This is just too awful. Such an amazing talent gone too soon. Wham was part of the soundtrack to my teenage years."