"The Greatest" has become "The Immortal."

A three-time heavyweight champion in the ring and an undisputed cultural phenomenon outside of it, Muhammad Ali died Friday night at a Phoenix-area hospital after battling respiratory issues connected to his long-term Parkinson's disease, a family spokesman confirmed.

Ali 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," said family spokesman Bob Gunnell in a statement to NBC News.

As word of his death spread, sentiments expressed to CBS Sports were predictably reverential.

"Muhammad Ali was Jack Johnson, Joe Louis, Willie Pep, Sugar Ray Robinson, Michael Jordan and Secretariat all in one magnificent package," said Randy Gordon, former chair of the New York State Athletic Commission and author of Glove Affair, which was released in February. "There will never be anyone like him again."

Indeed, to say Ali blazed a trail would be an understatement.

Born Cassius Marcellus Clay, he leapt from Louisville, Kentucky, to the world stage as an 18-year-old gold medalist at the 1960 Summer Olympics and turned professional six weeks later with a six-round decision over Tunney Hunsaker.

Clay was just 22 when he began his first reign as world heavyweight champion with a shocking defeat of Sonny Liston, then he repeated the feat -- after converting to Islam and changing his name -- with a first-round stoppage 15 months later.

"When I hear his name, I immediately think that he's the most iconic figure in boxing history," former lightweight champion Ray Mancini said. "The only one that's been bigger than the sport."

Eight successful title defenses followed before the most polarizing sequence of Ali's career, when he was reclassified as draft-eligible and ultimately refused induction into the U.S. Armed Forces in 1967 citing religious beliefs. He was stripped of his championship and his boxing license, remaining inactive for nearly four years as his felony case -- he was convicted in June 1967 and immediately appealed -- worked its way to the U.S. Supreme Court, which overturned it by a unanimous 8-0 vote.

"I'm not allowed to fight in America; I'm not allowed to leave America," he said at the time. "I've been persecuted before prosecuted."

The stance inspired lingering bitterness in some circles and life-long hero worship in others. It also cost Ali some of the prime years of his legendary career.

"When I look back at his times, the thing that stands out is his undying belief in himself," said Antonio Tarver, a former light heavyweight and cruiserweight champion who now competes as a heavyweight.

"He showed the world what only he could see."

Upon his return, Ali recorded two tuneup victories before meeting Joe Frazier on March 8, 1971 in a matchup of an undefeated former champion and the undefeated new champion who ascended in his absence.

The "Fight of the Century" generated unprecedented interest, yielded unprecedented revenue numbers and ended in Ali's first loss, via unanimous 15-round decision in the first of what would become a three-bout series between the rivals. The rivalry culminated with Ali's TKO victory at the "Thrilla in Manila" more than four years later.

Muhammad Ali battled Parkinson's disease for more than 30 years. Getty Images

In between, Ali lost another fight -- a 1973 decision to Ken Norton in which he suffered a broken jaw -- and won 17 others, including a scorecard defeat of Frazier that squared their series at 1-1 and an eighth-round KO of George Foreman in Zaire that began a second title reign in October 1974.

"My great-grandfather was a huge sports fanatic," Tarver said. "I can remember watching his fights on a small black and white."

Ali took his globe-trotting act to Puerto Rico, Malaysia and Germany, too, before losing the crown to relative novice Leon Spinks in the winner's eighth pro fight in February 1978. Ali regained the championship for the final time in New Orleans later that year in what turned out to be his last victory, though he did launch two ill-fated comebacks -- resulting in résumé-smearing losses to Larry Holmes in October 1980 and Trevor Berbick in December 1981.

The loss to Holmes, in which Ali was thrashed for 10 rounds before his corner surrendered, was the only time he was stopped; it is widely seen as the catalyst for the condition that progressively robbed him of his ability to speak and move effectively -- leading to declining appearances in the spotlight he'd always commanded.

"I interacted with him at [daughter] Laila's fight in [Washington] D.C. years ago with his entire family. I witnessed the magician himself. Just a gentle soul of a man," Tarver said. "Saw him last at Angelo Dundee's funeral, and for some reason, I recall not wanting to take a picture of him in that condition. It broke my heart."

A frail, declining Ali last appeared in public at a charity event two months ago, but Mancini said he would prefer to remember the good moments long before the others.

"My favorite memory is when Muhammad and myself were on a four-city bus tour, campaigning for his attorney and my friend, Ron DiNicola, for Pennsylvania Congressman," he said. "It was me and my nephew, Ali and Howard Bingham, his friend and photographer, along with Ron. We talked, joked and laughed for six hours. Before we departed, he told me, 'You remind me of Elvis. Elvis was cool.'

"I got a kick out of that."

Muhammad Ali is dead at the age of 74. Getty Images