UFC

Stars of sports and entertainment react to Muhammad Ali's death

Close-up of American boxer Muhammad Ali (formerly known as Cassius Clay) as he leans on the ropes during a break in training, 1967. (Photo by Robert Abbott Sengstacke/Getty Images)

Close-up of American boxer Muhammad Ali (formerly known as Cassius Clay) as he leans on the ropes during a break in training, 1967. (Photo by Robert Abbott Sengstacke/Getty Images)

Three time heavyweight champ Muhammad Ali, a sports legend and iconic humanitarian and activist, passed away Friday in Arizona at the age of 74 after a long battle with Parkinson's disesase.

Tributes and condolences flowed into Twitter for The Greatest.

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