- Muhammad Ali universally acknowledged as "The Greatest" boxer of all time
- He was a global icon whose fame spread far beyond the sporting arena
(CNN)"I am the greatest."
It's easy to say -- but much harder to convince millions of people around the world that you're right.
A conversation about Muhammad Ali could go on for hours before even beginning to touch on the sporting legacy he left in the ring.
His charisma, charm, quick wit and ability to turn a phrase were just some of the qualities that made him a truly global icon.
He transcended boxing.
It says a lot about him that many sporting icons look up to Ali in much the same way as his hordes of "ordinary" fans.
"Muhammad Ali, when I started boxing, was one of my inspirations," Manny Pacquiao, another of boxing's all-time greats, told CNN after Ali's death was announced.
"I always admired him and I always thought 'This is my inspiration, why I am here in boxing.'
"We all know what he has done and accomplished. He's an inspiration to all boxers."
Pacquiao said Ali's death, at the age of 74, following years of ill health was "a big loss for boxing," but that his legend would live on.
"He passed away, but the memory of Muhammad Ali and his accomplishments we will never forget."
While mourning is inevitable when someone of Ali's stature passes away, it also has served as an opportunity to celebrate his life.
"Every fiber of his being was great," said David Haye, a fellow former heavyweight world champion.
"His personal and religious beliefs were so strong that he lost three and a half of his best years because of a decision he made not to go to Vietnam.
"At the time it was a very unpopular decision, he lost an amazing amount of his fan base, the American media turned on him but he stuck by it and years later people look back and think what an amazing stand.
"The fact that he believed so strongly about that, shows he wasn't only the greatest in the ring, he was the greatest outside of the ring as well."
Three-time heavyweight champion
Many boxing fans and journalists might tell you Ali isn't the best boxer in history -- that honor often goes to Sugar Ray Robinson. But comparing boxers across different eras and weight classes is a fruitless exercise.
His unorthodox style, quick feet and lightning-fast reflexes saw Ali crowned world heavyweight champion an unprecedented three times and won him legions of admirers along the way.
Ali took on all challengers -- even when onlookers didn't give him a chance -- and beat most, recording just five losses over the course of his professional career.
Most laughed at the idea of a 22-year-old Ali defeating the fearsome and hard-hitting Sonny Liston, but that's what he did when the fighters met in 1964 -- and then again a year later.
But Ali's athletic achievements didn't define him -- they were just part of a package and it was perhaps what he did outside of the ring that turned him into the man we know.
In 1967, Ali's refusal to be inducted into the U.S. armed forces -- due to personal and religious beliefs -- subsequently earned him a three-year ban from boxing, robbing him of his peak years as a professional fighter.
Initially reviled for his anti-war stance, Ali was branded a traitor but began to gain sympathy during his exile as criticism of the Vietnam War intensified.
Ali famously claimed, "I have no quarrel with the Viet Cong," and by the time his boxing ban was overturned in 1971, most of America didn't either.
As CNN political commentator and professor Marc Lamont Hill put it: "Ali didn't change, the world did."
Controversial anti-war stance
Ali was born in 1942 in Louisville, Kentucky, during a time of severe racial segregation.
The fighting in Vietnam saw young, black men lose their lives and Ali used his position as a prominent figure -- earned through his success in the ring -- to denounce this.
"He spoke to governments, he stood up against a war in Vietnam," said Chris Eubank, a former British boxer.
"He was stripped of his championship because of his refusal to go to war. That statement is what makes him stand out from any other sportsman in history.
"He has become an icon because of it. It's not just his boxing ability, it's what he used the platform for. In standing up for human rights, and not going to the Vietnam War.
"He is a man who stands out from the pack and [that] has made him a beacon of light, an inspiration and an example so that is why he is by far the top sporting legend of our time."
The world of sport has lost a hero and, for now, we'll have to come to terms with living without a truly unique character.
"We will never see anyone like him again, you'll never see another Muhammad Ali," Haye, the former boxer, says. "He's one of a kind. We will never see 50% of what he was ever again."