Muhammad Ali has died in a Phoenix-area hospital where he was battling respiratory issues ... according to a family spokesman.
The legendary boxer and humanitarian was 74 years old. He had checked into the hospital on Thursday and reps said he was in fair condition, but on Friday his health worsened throughout the day.
The family says his funeral will be held in Ali's hometown of Louisville, although the spokesman didn't specify a date. NBC News first reported his death.
Ali will be remembered as one of the most recognized figures worldwide -- after winning boxing's heavyweight title 3 different times ... with the first coming in a KO of Sonny Liston in 1964.
He was as famous for his boxing matches -- the "Rumble in the Jungle," the "Thrilla in Manila" -- as quotes like, "Float like a butterfly, sting like a bee."
Ali, born Cassius Clay, changed his name and converted to Islam in 1964. He also famously refused to enter the Vietnam War in 1967 as a conscientious objector.
Although he was diagnosed with Parkinson's Disease in 1984 ... Ali remained very active at international events in and out of the sporting world. His lighting of the Olympic flame at the 1996 Atlanta games is considered one of the most iconic images in Olympic history.
The champ is survived by his wife Yolanda Williams and 9 children -- 7 daughters, 2 sons -- including Laila Ali, who became an undefeated boxing champ herself.
When he retired in 1981, Ali had 56 wins, 5 losses and 37 knockouts.
He was inducted into the International Boxing Hall of Fame in 1990 ... and will always hold the title of "The Greatest."