Muhammad Ali, the silver-tongued boxer and civil rights champion who famously proclaimed himself "The Greatest" and then spent a lifetime living up to the billing, is dead.

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, 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.

His daughter Rasheda said early Saturday that the legend was "no longer suffering," describing him as "daddy, my best friend and hero" as well as "the greatest man that ever lived."

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.

Born Cassius Marcellus Clay on Jan. 17, 1942 in Louisville, Kentucky, to middle-class parents, Ali started boxing when he was 12, winning Golden Gloves titles before heading to the 1960 Olympics in Rome, where he won a gold medal as a light heavyweight.

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.

As his profile rose, Ali acted out against American racism. After he was refused services at a soda fountain counter, he said, he threw his Olympic gold medal into a river.

Recoiling from the sport's tightly knit community of agents and promoters, Ali found guidance instead from the Nation of Islam, an American Muslim sect that advocated racial separation and rejected the pacifism of most civil rights activism. Inspired by Malcolm X, one of the group's leaders, he converted in 1963. But he kept his new faith a secret until the crown was safely in hand.

How the world mourned Muhammad Ali:
From global leaders and pop stars to top athletes, the world paused to remember the legend, Muhammad Ali who dazzled with his lightning fast jabs, his equally quick wit and unwavering principles.

The famed boxer and icon died at the age of 74, after spending 32 years fighting Parkinson's disease. His name trended all over social media with hashtags such as the Greatest of All Time or #GOAT for short, and Rest in Power.

"To the African-American community, he was a black man who faced overwhelming bigotry the way he faced every opponent in the ring: fearlessly," wrote NBA legend Kareem Abdul-Jabbar on Facebook.
Muhammad Ali: Boxing legend, activist and 'The Greatest'
Tributes came from his once-fiercest foes in the ring.
George Foreman, the two-time heavyweight champion, who lost to Ali in the 1974 Rumble in the Jungle, mourned whom he called "the greatest piece."

Fans remembered him beyond his athletics skills, including the sacrifices he made to stand up against the Vietnam War draft -- even when his stance was unpopular. That steadfastness won him respect, boxing promoter Don King told CNN.
"People who didn't like him had to respect him," he said.
To African Americans, he was a hero who refused to bow in the face of racism.

Ali was a man who was proud of his religion and had changed his name to reflect his faith.
W. Kamau Bell, host of United Shades of American tweeted to "also remember that he was a Muslim."