Ali, 72, is widely considered the greatest fighter in boxing history. In 61 fights, he finished 56-5 with 37 knockouts. Ali also won the heavyweight crown three times, the first boxer to do so. Born Cassius Marcellus Clay, Jr., he changed his name to Muhammad Ali after joining the Nation of Islam.
Ali has battled Parkinson's for decades. In October, Rahman Ali reportedly said his brother's health ahd declined to the point where he was too ill to speak, according to The Courier-Journal. Ali later refuted the reports on Twitter, as did his family's spokesman.
"Muhammad is doing fine at this point," family spokesman Bob Gunnell said in October. "His speaking style is lower in tone, and as the day goes on, he doesn't speak as well as he does in the morning. But Muhammad's a strong person for his age and for the disease he has."
- Mike Fiammetta