World champion heavyweight boxer, Muhammad Ali, was born Cassius Marcellus Clay, Jr. on 17 January, 1942 in Louisville, Kentucky. Ali won 56 out of 61 boxing matches, with 37 of the wins from knockout(K.O.)punches. He is considered by many to be one of the greatest boxers of all time and is known for his phrase "float like a butterfly and sting like a bee" to describe his unconventional defense style of moving around to avoid a punch rather than conventionally blocking his face with his hands.
Muhammad Ali no longer wanted to be known as Cassius Clay when he became involved with the Nation of Islam. Many members of the Nation of Islam gave up their surnames and took new names because white men had given the surnames to their ancestors who were slaves. Ali would not fight for the United States in the Vietnam war or be referred to as Cassius Clay. As a result, he received a five year prison sentence for refusing to serve in the United States Army and the United States professional boxing commission banned him from professional boxing for three years.
Muhammad Ali made his living during those rough years as a speaker against the Vietnam war. He often accompanied Elijah Muhammad, the leader of the Nation of Islam, at rallies in the late 1960s. He received his boxing license back in 1970 and the United States Supreme Court overturned his prison conviction in 1971.
Ali's boxing match against Joe Frazier on 8 March 1971 was called "The Fight of the Century" and the heavyweight crown was at stake. Frazier won that fight and it was Ali's first loss as a professional boxer. However, Muhammad Ali won the heavyweight boxing championship title against George Foreman on 30 October 1974 in Zaire.
Ali had another well-received boxing match with Joe Frazier in 1975, but the fight was not finished as Frazier's eyes would not reopen during the fight. Frazier only had two more fights after that before he went into retirement. Also in 1975, Ali became a Sunni Muslim due to changes that the Nation of Islam was making toward becoming Sect Sunni Islam.
In 1977 Ali's trainers and doctors tried to convince him to retire as some of his body's reflexes were beginning to fail. Muhammad Ali would not retire and lost a 15 February, 1978 boxing championship fight against a young Olympic champion named Leon Spinks. Ali and Spinks had a rematch seven months later and Mohammad Ali won the fight.
On 27 June 1979 Muhammad Ali announced he was retiring, but the next year he was back fighting Larry Holmes despite a Mayo Clinic examination that had found a hole in Ali's brain. He was beginning to experience slurred speech and numbness in his hands and he lost to Holmes. On 11 December, 1981 Ali fought one more time — against upcoming young boxer Trevor Berbick — and lost that match as well. Ali was diagnosed with Parkinson's disease and retired from boxing permanently.