Muhammad Ali is a former American boxer, one of the greatest heavyweight fighters of all time. He is known the world over for his boxing career as well as his politcal activism. He received Sports Illustrated’s title of Sportsman of the Century in 1999. Childhood and youthful career Muhammad Ali was born Cassius Marcellus Clay Jr., in Louisville, Kentucky. Cassius was named after his father. His boxing career was sparked at the age of 12, after someone stole his bicycle. Cassius reported it to a local policeman, Joe Martin, and told the officer he was going to beat up the person who stole his bike. Martin replied that he had better learn to fight first. That was the beginning of the youngster's climb to the top of the boxing game. Officer Martin trained young Cassius, who advanced through the youth ranks quickly. Cassius Clay won the gold medal as a light heavyweight boxer at the 1960 Summer Olympics in Rome. Legend has it that he threw the medal into the Ohio River after being denied service at a whites-only restaurant, but his version was that he simply lost it. Clay was presented with a replacement at the 1996 Games in Atlanta, Georgia. Going pro Under legendary trainer Angelo Dundee, Clay entered professional boxing in 1960. He picked up the nickname "Louisville Lip" by composing poems and predicting in which round he would knock out his opponent. He boisterously sang his own praises with such sayings as "I am the greatest," and "I'm young, I'm pretty, I'm fast, and no one can beat me." Clay won his first professional fight in November 1960, against Tunney Hunsaker. From 1960 to 1963, the young boxer built a record of 19-0, with 15 knockouts. He was the number-one contender for Sonny Liston's heavyweight title. A bout was set for February 25, 1964; during the weigh-in, the boisterous Clay declared that he would "float like a butterfly, sting like a bee." The saying became as famous as Clay. He won the fight before the seventh round when Liston retired to his stool and later claimed he had a separated shoulder. Proclaiming himself “King of the World," Clay was crowned the heavyweight champion, which he reconfirmed in a rematch against Liston in May 1965. Joining the Nation While training for the title bout against Liston, Clay met Cap’n Sam, a Nation of Islam minister of the local Miami mosque. He introduced Clay to NOI spokesman, Malcolm X. Malcolm and Cassius bonded on a deep level. Malcolm X brought Clay into the Nation of Islam. The day after he won the heavyweight title, the new champ announced to the world that he was now a member of the Nation of Islam, and his name was now Cassius X. That name lasted only a short time before he was renamed Muhammad Ali by the NOI founder, Elijah Muhammad. Herbert Muhammad became Ali’s new manager. Refusing to fight With the Vietnam War worsening, Ali was called up for induction into the armed forces in 1967. He refused, based on the grounds of religious beliefs; he was a practicing Muslim minister. That refusal led to the now-famous Ali quote, "I ain’t got no quarrel with them Vietcong...." Ali's refusal sparked a national uproar, and virtually every state and local entity canceled his boxing license. Ali did not fight for two and a half years. He was stripped of his championship title, and his passport was confiscated. He lost an initial court battle and faced a five-year prison term. Ali became the first national figure to speak out against the war in Vietnam. Back in the ring Ali managed to get his boxing license reinstated in 1970, thus allowing the “Fight of the Century” against Joe Frazier in Madison Square Garden. The fight was held in March 1971. Frazier knocked Ali down in the seventh round. Numerous followers of the sport believed that, had Ali not been unable to box for more than two years, he could have won the fight. In fact, Ali beat Frazier in a 1974 rematch. In October 1974, Muhammad Ali and George Foreman battled in the bout dubbed “Rumble in the Jungle,” held in Zaire. Ali absorbed everything Foreman dished out. He waited until Foreman was exhausted, then went in for the knockout, sending him down in the eighth round. As a result of that fight, Ali was awarded the 1974 Hickok Belt as top professional athlete of the year, and Sports Illustrated magazine's Sportsman of the Year award. The “Thrilla in Manila” was held in 1975, when Ali defeated Joe Frazier again. That fight became one of the most well-known heavyweight bouts ever. After the 14th round, Frazier’s trainer refused to let him return to the ring, and Ali won by a technical knockout (TKO). Ali would keep his title until 1978, when he lost to Leon Spinks. Ali defeated Spinks in a rematch and won the heavyweight championship record for a third time. The champ retired in 1981, with a career record of 56 wins (37 by knockout) and five losses. The price of boxing In 1984, Ali was diagnosed with pugilistic Parkinson's syndrome, from which his motor functions had begun a slow decline. Ali remains a hero to millions, and in 1996, he was given the honor of lighting the Olympic flame in Atlanta, Georgia. He also received the Presidential Medal of Freedom in November 2005. In the same month, the $60 million Muhammad Ali Center opened in downtown Louisville, Kentucky. The facility displays boxing memorabilia and focuses on peace, social responsibility, respect, and personal growth. Muhammad Ali has been married four times and has nine children. He currently lives in Michigan with his fourth wife, Yolanda Williams.