From Cassius Clay to Muhammad Ali : a life in pictures

Ali's death was confirmed in a statement issued by family spokesman Bob Gunnell late evening, a day after he was admitted to a Phoenix-area hospital with a respiratory ailment. The cause of death or the name of the hospital where he died were not immediately disclosed. Ali had long suffered from Parkinson's syndrome, which impaired his speech and made the once-graceful athlete almost a prisoner in his own body.

Even so, Ali's youthful proclamation of himself as "the Greatest" rang true until the end for the millions of people worldwide who admired him for his courage both inside and outside the ring. "A part of me slipped away, the greatest piece," George Foreman, a former heavyweight boxer and one of Ali's most formidable opponents in the ring, said on Twitter after the news of Ali's death. Roy Jones Jr, a former champion boxer who grew up during Ali's prime, also said on Twitter: "My heart is deeply saddened yet both appreciative and relieved that the greatest is now resting in the greatest place."

During and after his championship reign, Ali met scores of world leaders, travelled to promote Islam and for a time he was considered the most recognisable person on earth, known even in remote villages far from the US. Al Jazeera's Rob Reynolds, reporting from Los Angeles, said: "Ali was a product of his time, of the civil rights movement, of the Black Power movement. Coming of age, he was the symbol of the emergence of that way of thinking in the US.