In this Sept. 17, 1974, file photo, Muhammad Ali is greeted in downtown Kinshasa, Zaire (AP)
Quotes from around the world about the death of three-time heavyweight champion Muhammad Ali:
President Barack Obama says Muhammad Ali "shook up the world and the world is better for it."
Obama says he keeps a pair of Ali's gloves on display in his private study, just off the Oval Office and under the famous photograph of the young champion "roaring like a lion over fallen Sonny Liston."
Obama says in a statement that Ali "fought for what was right," stood with Martin Luther King Jr. and Nelson Mandela "when it was hard" and "spoke out when others wouldn't."
Obama says even as Ali's physical powers were in decline, the boxing great "became an even more powerful force for peace and reconciliation around the world."
The president says Parkinson's disease may have "ravaged" Ali's body, but it "couldn't take the spark from his eyes."
''He's the most transforming figure of my time, certainly. He did more to change race relations and the views of people than even Martin Luther King. It was a privilege and an honor for me to know him and associate with him.'' - Bob Arum, who promoted 26 of Ali's fights.
Ali, Frazier & Foreman we were 1 guy. A part of me slipped away, ''The greatest piece'' - tweet by George Foreman, Ali's opponent in the ''Rumble in the Jungle''
''Muhammad Ali is a legend and one of the world's most celebrated athletes, the fighter who ushered in the golden era of boxing and put the sport on the map. He paved the way for professional fighters, including myself, elevating boxing to become a sport watched in millions of households around the world'' - Boxer Oscar De La Hoya, who won titles at six different weight classes.
''We lost a giant today. Boxing benefited from Muhammad Ali's talents but not nearly as much as mankind benefited from his humanity. Our hearts and prayers go out to the Ali family. May God bless them.'' - Boxer Manny Pacquiao, a champion in eight weight classes.
''Passing the Olympic torch to Muhammad to light the cauldron at the Atlanta Games in 1996 was the defining moment of my career, and a memory I will treasure forever, as much as any of the medals I won. As Olympians, our role is to inspire others to achieve their dreams, and no person has ever lived that role more than Muhammad Ali.'' - swimmer Janet Evans.
''Without question his legacy is one that he defied the odds because he stood up for what he believed in and when he was put to the test he took personal harm rather than go against his beliefs and what he stood for.'' - Don King, promoter of ''Rumble in the Jungle'' and ''Thrilla in Manilla.''
''We are proud to call Ali not only a member of Team USA, but an Olympic champion. With unparalleled grit and determination, he left a legacy that will continue to inspire generations of Americans for years to come.'' - Scott Blackmun, CEO of the U.S. Olympic Committee.
''Hillary and I are saddened by the passing of Muhammad Ali. From the day he claimed the Olympic gold medal in 1960, boxing fans across the world knew they were seeing a blend of beauty and grace, speed and strength that may never be matched again. We watched him grow from the brash self-confidence of youth and success into a manhood full of religious and political convictions that led him to make tough choices and live with the consequences. Along the way we saw him courageous in the ring, inspiring to the young, compassionate to those in need, and strong and good-humored in bearing the burden of his own health challenges. I was honored to award him the Presidential Citizens Medal at the White House, to watch him light the Olympic flame, and to forge a friendship with a man who, through triumph and trials, became even greater than his legend. Our hearts go out to Lonnie, his children, and his entire family.'' - President Bill Clinton.
''He was an athlete who touched the hearts of people across the globe, an athlete who was engaged beyond sport, an athlete who had the courage to give hope to so many suffering illness by lighting the Olympic cauldron and not hiding his own affliction. He was an athlete who fought for peace and tolerance - he was a true Olympian. Meeting him in person was an inspiration. He was a man who at the same time was so proud and yet so humble.'' - IOC President Thomas Bach.
''Muhammad Ali was not just a champion in the ring - he was a champion of civil rights, and a role model for so many people.'' - British Prime Minister David Cameron.
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