Ali died Friday at a Phoenix-area hospital, where he had spent the past few days being treated for respiratory complications, a family spokesman confirmed to NBC News. He was 74.
"After a 32-year battle with Parkinson's disease, Muhammad Ali has passed away at the age of 74. The three-time World Heavyweight Champion boxer died this evening," Bob Gunnell, a family spokesman, told NBC News.
Ali had suffered for three decades from Parkinson's Disease, a progressive neurological condition that slowly robbed him of both his legendary verbal grace and his physical dexterity. A funeral service is planned in his hometown of Louisville, Kentucky.
Even as his health declined, Ali did not shy from politics or controversy, releasing a statement in December criticizing Republican presidential candidate Donald Trump's proposal to ban Muslims from entering the United States. "We as Muslims have to stand up to those who use Islam to advance their own personal agenda," he said.
The remark bookended the life of a man who burst into the national consciousness in the early 1960s, when as a young heavyweight champion he converted to Islam and refused to serve in the Vietnam War, and became an emblem of strength, eloquence, conscience and courage. Ali was an anti-establishment showman who transcended borders and barriers, race and religion. His fights against other men became spectacles, but he embodied much greater battles.
He turned professional shortly afterward, supported at first by Louisville business owners who guaranteed him an unprecedented 50-50 split in earnings. His knack for talking up his own talents — often in verse — earned him the dismissive nickname "the Louisville Lip," but he backed up his talk with action, relocating to Miami to train with the legendary trainer Angelo Dundee and build a case for getting a shot at the heavyweight title.
That came the following year, when heavyweight champion Sonny Liston agreed to fight Ali. The challenger geared up for the bout with a litany of insults and rhymes, including the line, "float like a butterfly, sting like a bee." He beat the fearsome Liston in a sixth-round technical knockout before a stunned Miami Beach crowd. In the ring, Ali proclaimed, "I am the greatest! I am the greatest! I'm the king of the world."