Boxing great Muhammad Ali waves to the crowd during the opening ceremony of the World Equestrian Games in Lexington, Kentucky, in this September 25, 2010 file photo.
U.S. President Barack Obama and United Nations Secretary-General Ban Ki-moon on Saturday led a chorus of world dignitaries marking the death of Muhammad Ali.
The boxing titan, humanitarian and civil rights activist, hospitalized with a respiratory infection, died Friday at age 74.
Obama, in a statement, likened the firebrand Ali to Nelson Mandela and Martin Luther King, Jr., saying Ali "shook up the world, and the world is better for it." Obama also posted a picture of himself sitting beneath the iconic ring photo of Ali standing over a defeated Sonny Liston after retaining the heavyweight championship in 1965.
“Rest in peace, Champ,” Obama tweeted.
U.N. chief Ban issued a statement describing how the world body "benefited from the life and work of one of the past century's great humanitarians and advocates for understanding and peace."
Former president Bill Clinton, who awarded Ali the Presidential Citizens Medal before leaving office in 2001, paid tribute in another tweet: “Goodbye my friend. You were Great in so many ways.”
The former president also issued a statement with his wife, Democratic presidential contender Hillary Clinton, that sought to capture Ali's unparalleled athleticism.
“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,” he said.
Republican presidential candidate Donald Trump also tweeted a tribute to Ali: “A truly great champion and a wonderful guy. He will be missed by all!"
Muhammad Ali: A Legend And A Cultural Icon Dead at 74
1/21Boxing legend Muhammad Ali stands with his wife Yolanda as he is introduced before the welterweight fight between Floyd Mayweather Jr. and Shane Mosley at the MGM Grand Garden Arena in Las Vegas, Nevada in this May 1, 2010 file photo.
2/21FILE - Muhammad Ali, world heavyweight champion, punches speed bag at the Folk Art Center in Manila, Philippines, Sept. 29, 1975, as he prepares his title fight on October 1 with Joe Frazier.
3/21FILE - Muhammad Ali speaks to Muslims holding a book called "Towards Understanding Islam" written by Sayyid Abul Ala Maududi in London, Britain, May 1966. Ali died late Friday in Phoenix, Arizona, June 3, 2016.
4/21FILE - The Beatles, from left, Paul McCartney, John Lennon, Ringo Starr and George Harrison take a fake blow from Cassius Clay, who later changed his name to Muhammad Ali, while visiting the heavyweight contender in Miami Beach, Fla., Feb. 18, 1964.
5/21FILE - Heavyweight boxing champion Muhammad Ali is escorted from the Armed Forces Examining and Entrance Station in Houston by Lt. Col. J. Edwin McKee, after Ali refused Army induction, April 28, 1967. Ali died at age 74, June 3, 2016.
6/21FILE - Heavyweight Champion Muhammad Ali exclaims "Why me?" when informed his draft board in Louisville, Ky., had reclassified him 1-A in the draft, Feb. 17, 1966. Ali surrounded himself with youngsters from his neighborhood as he told of his feelings in
7/21FILE - U.S. boxing great Muhammad Ali poses during the Crystal Award ceremony at the World Economic Forum (WEF) in Davos, Switzerland, Jan. 28, 2006.
8/21FILE - Spray flies from the head of challenger Joe Frazier as heavyweight champion Muhammad Ali connects with a right in the ninth round of their title fight in Manila, Philippines, Oct. 1, 1974. Ali has died, his family said, June 3, 2016. He was 74.
9/21A visitor is interviewed in reaction to the death of heavyweight boxer Muhammad Ali at the "I Am The Greatest, Muhammad Ali" exhibition at the O2 arena, which hosts high profile boxing fights in London, Saturday, June 4, 2016.
10/21Former boxing great Muhammad Ali is given the Courage Award by singer Whitney Houston at the GQ Men of the Year awards show in New York in this October 21, 1998 file photo.
12/21World heavyweight boxing champion Muhammad Ali visited the pyramids area, rode a horse and a camel and shook hands with the Bedouins who guard the huge monuments there, May 30, 1966.
14/21FILE - President George W. Bush presents the Presidential Medal of Freedom to boxer Muhammad Ali in the East Room of the White House, Nov. 9, 2005.
15/21Retired boxing champion Muhammad Ali waves after he received the Liberty Medal for his humanitarian work, during a ceremony at the National Constitution Center, Thursday, Sept. 13, 2012, in Philadelphia. (AP Photo/Matt Rourke)
16/21FILE - Heavyweight champion Muhammad Ali stands over fallen challenger Sonny Liston, shouting and gesturing shortly after dropping Liston with a short hard right to the jaw, in Lewiston, Maine, May 25, 1965.
17/21FILE - Young heavyweight boxer Cassius Clay, who later changed his name to Muhammad Ali, points to a sign he wrote on a chalk board in his dressing room before his fight against Archie Moore in Los Angeles, predicting he'd knock Moore out in the fourth ro
18/21FILE - World heavyweight boxing champion Muhammad Ali, right, and Black Muslim leader Malcolm X in New York City, March 1, 1964. Ali died Friday in Phoenix, Arizona, at age 74.
19/21FILE - Muhammad Ali, former world heavyweight boxing champion, toys with the finely combed hair of television sports commentators Howard Cosell before the start of the Olympic boxing trials, in West Point, N.Y., Aug. 7, 1972.
20/21FILE - An Oct. 30, 1974 file photo shows Challenger Muhammad Ali watching as defending world champion George Foreman goes down to the canvas in the eighth round of their WBA/WBC championship match in Kinshasa, Zaire.
21/21Boxing great Muhammad Ali waves to the crowd during the opening ceremony of the World Equestrian Games in Lexington, Kentucky, in this September 25, 2010 file photo.
Basketball great-turned-journalist Kareem Abdul-Jabbar remembered the controversial Ali as a friend and mentor whose "greatness was his ability to be different things to different people."
In a lengthy essay Saturday, Abdul-Jabbar remembered Ali as an "unparalleled champion, faster and smarter than any heavyweight." He also cited Ali for giving voice to anti-establishment, anti-war American youth of the 1960s, describing him as "a defiant voice against the Vietnam war... ."
"To the African American community," Abdul-Jabbar wrote, "he was a black man who faced overwhelming bigotry the way he faced every opponent in the ring: fearlessly."
Brazilian soccer icon Pele used social media to lament the death, noting that “the sporting universe has just suffered a big loss. ... The sadness is overwhelming.”
Argentina’s Diego Maradona wrote “the best of all time has left... How can I not feel this loss... Surely he left because he could no longer give us more happiness. My condolences to his family.”
More coverage planned
Muhammad Ali will appear on the cover of Sports Illustrated June 13 - his 40th time as the magazine's top story. The article will include a 1970 photo showing Ali training in Miami Beach for his return to the ring after a three-year ban for refusing induction into the U.S. armed services.
In explaining his editorial decision, SI executive Paul Fichtenbaum described Ali as "a singular force of athletics, humanitarianism and social equality unlike anyone in our history.”
