Significant figures from across the world, and from all walks of life, have paid tribute to Muhammad Ali following his death at the age of 74.
Arguably the most iconic figure the world of sport has ever known, his prodigious talent and seductive personality alone would have been enough to ensure his legend lived forever.
But Ali's importance reached out far beyond the ring. As a champion of the civil rights movement, he was an inspiration to many, including US president Barack Obama who revealed how the three-time world heavyweight helped to shape his own life as a young man.
"'I am America,' he once declared," Obama said in a statement after the news broke of Ali's death.
"'I am the part you won't recognize. But get used to me -- black, confident, cocky; my name, not yours; my religion, not yours; my goals, my own. Get used to me.' That's the Ali I came to know as I came of age -- not just as skilled a poet on the mic as he was a fighter in the ring, but a man who fought for what was right. A man who fought for us."
He shook up the world, and the world's better for it. Rest in peace, Champ. pic.twitter.com/z1yM3sSLH3
-- President Obama (@POTUS) June 4, 2016
Obama revealed he keeps a pair of Ali's gloves on display in the White House, under the iconic 1965 picture of Ali standing over a fallen Sonny Liston.
"I was too young when it was taken to understand who he was -- still Cassius Clay, already an Olympic Gold Medal winner, yet to set out on a spiritual journey that would lead him to his Muslim faith, exile him at the peak of his power, and set the stage for his return to greatness with a name as familiar to the downtrodden in the slums of Southeast Asia and the villages of Africa as it was to cheering crowds in Madison Square Garden," Obama said.
The President added: "He wasn't perfect, of course. For all his magic in the ring, he could be careless with his words, and full of contradictions as his faith evolved. But his wonderful, infectious, even innocent spirit ultimately won him more fans than foes -- maybe because in him, we hoped to see something of ourselves."
His daughter Hana Ali posted a heartfelt message on Twitter, in which she described her father's final hours before he died at a Phoenix hospital of septic shock caused by "unspecified natural causes".
The boxing community was unanimous in its gratitude for the legacy left in their sport by a man who described himself as 'The Greatest'. It was a title that no-one ever felt moved to question.
-- Mike Tyson (@MikeTyson) June 4, 2016
Hana Ali & the whole family, my heart goes out you. Muhammad Ali has been a fine man. That will never die. pic.twitter.com/3L5HK0zPCb
-- George Foreman (@GeorgeForeman) June 4, 2016
-- Frank Bruno MBE (@frankbrunoboxer) June 4, 2016
Rip the greatest of all times in many different ways. ????
-- #Gypsyking (@Tyson_Fury) June 4, 2016
He was and still is an inspiration to so many. RIP the greatest ? pic.twitter.com/tOUA2YKuhF
-- Anthony Joshua (@anthonyfjoshua) June 4, 2016
Ali's former promoter Don King told CNN: "Let us celebrate his life. This is not a time to mourn. This is a time to try to emanate the job he was doing and the burden he leaves behind for us to carry on, to remember that the people are the most important."
Sir Michael Parkinson famously had a series of explosive interviews with the boxer.
Sir Michael remembered Ali as "the most extraordinary man I ever met" - one of two people who could add an extra two million viewers to his show, and the person who eclipsed every one of the thousands of others he has interviewed.
He told the BBC: "When you look back over a career such as I have had and you look at all the thousands of people that you've interviewed, a few stand out. And he was the one who stands out most of all. An extraordinary man, and you are lucky to have met him. His image will live on and his memory will live on for the rest of time, I suppose, because he did actually change boxing.
"He persuaded into arenas people who hitherto had thought boxing was repulsive or indeed had no interest whatsoever. He was more than box office."
Ali's rise to fame came at the same time Beatlemania swept the world in the 1960s and Sir Paul McCartney paid his tribute to Ali, saying: "I loved that man. He was great from the first day we met him in Miami, and on the numerous occasions when I ran into him over the years.
"Besides being the greatest boxer, he was a beautiful, gentle man with a great sense of humour who would often pull a pack of cards out of his pocket, no matter how posh the occasion, and do a card trick for you. The world has lost a truly great man."
Ali was also an inspiration for sufferers of Parkinson's disease after he battled the illness for three decades and became a humanitarian following his retirement from the ring in 1981.
Fellow Parkinson's disease sufferer Michael J Fox took to Twitter to pay his respects.
Ali, the G-O-A-T. A giant, an inspiration, a man of peace, a warrior for the cure. Thank you. pic.twitter.com/MCLyJhLC0X
-- Michael J. Fox (@realmikefox) June 4, 2016
Ali's funeral will take place in his home town of Louisville, Kentucky on June 10, where flags have been flying at half mast since his death was announced.
Former US president Bill Clinton and comedian Billy Crystal will deliver eulogies at the service, which will be open to the public. A procession will also be held in Louisville on the same day.