UNDATED (AP) — He called himself "The Greatest" while claiming the heavyweight title an unprecedented three times from 1964-78.

Muhammad Ali has died at age 74 following a short hospital stay near his Phoenix home. The death was confirmed in a statement released by his family.

Two people familiar with his illness say Ali had been hospitalized with respiratory issues complicated by the Parkinson's that he was diagnosed with in the 1980s.

Ali has been hospitalized several times in recent years, most recently in early 2015 for a severe urinary tract infection initially diagnosed as pneumonia.

The boxing icon was born Cassius Clay in 1942 and won a gold medal as a light heavyweight at the 1960 Rome Olympics. He turned pro at age 18 later that year shocked the boxing community by beating the heavily-favored Sonny Liston to win the heavyweight crown in 1964.

Ali changed his name following his conversion to Islam shortly after the first Liston fight. He beat Liston again the next year and also earned a TKO against former champ Floyd Patterson in 1965 before he refused induction into the U.S. armed services two years later, costing him his title. He was convicted of draft evasion, a decision that was unanimously overturned by the US Supreme Court.

He didn't fight for 3 1/2 years before beginning a comeback attempt in October 1970. He fought Joe Frazier for the heavyweight title in March 8, suffering his first loss in the ring.

Ali eventually regained the title with a 1974 victory over George Foreman following a win over Frazier that year. He also beat Frazier in 1975 and retained the belts until a stunning loss to Leon Spinks in February 1978. Ali won back the title from Spinks later in 1978 before announcing his latest retirement, allowing Larry Holmes to take the belts. Ali returned to the ring in October 1980 against Holmes, who kept the crown with an 11th-round TKO.

Ali last fought in 1981 against Trevor Berbick and was diagnosed with Parkinson's disease three years later. He later served as a goodwill ambassador for numerous charitable and humanitarian functions, and lit the Olympic cauldron at the 1996 Atlanta Olympics.