Former world heavyweight champion Muhammad Ali died in Phoenix, Arizona on June 3 "after a 32-year battle with Parkinson's disease," his family said.
Ali, 74, one of the best-known figures of the 20th century, was hospitalized this week for a respiratory ailment, and media reports say his health fell rapidly.
Earlier in the day, Radar Online had reported that Ali had been placed on life support and not likely to live.
Ali had suffered from Parkinson's disease for more than three decades.
Despite the disease, he had kept up a busy appearance schedule until recently, though he had not spoken in public for years.
Doctors say the Parkinson's likely was caused by the thousands of punches Ali took during a career in which he traveled the world for big fights.
Former five division world champion Floyd Mayweather Jr. - regarded as the best boxer of this generation and the most financially successful fighter in boxing history, was saddened by the news of Ali's passing.
"Words can't explain what Muhammad Ali done for the sport of boxing. He's one of the guys who paved the way for me to be where I'm at today, so you know we lost a legend, a hero and a great man," Mayweather said.
