Muhammad Ali (born Cassius Marcellus Clay Jr., January 17, 1942 – June 3, 2016) was an American professional boxer widely regarded as one of the greatest athletes in history. He won the world heavyweight boxing championship three times and successfully defended the title 19 times during his career, which spanned from 1960 to 1981. Ali compiled a professional record of 56 wins, 5 losses, and 37 knockouts[1][4]. Ali began boxing at age 12 and won a gold medal in the light heavyweight division at the 1960 Rome Olympics[4][6]. He turned professional soon after and gained fame for his speed, footwork, and charismatic personality, often proclaiming himself "The Greatest." Key victories included defeating Sonny Liston in 1964 to become heavyweight champion, and later regaining the title in iconic bouts such as the 1974 "Rumble in the Jungle" against George Foreman and the 1975 "Thrilla in Manila" against Joe Frazier[1][2][3]. Outside the ring, Ali was known for his outspoken activism. He converted to Islam, joined the Nation of Islam, and took a strong public stance against the Vietnam War, refusing military induction on conscientious grounds, which led to a suspension from boxing for over three years[5]. His activism challenged racial inequality and war policies, making him a polarizing yet influential figure in American culture. After retiring, Ali remained a global ambassador for peace and humanitarian causes. He was inducted into the International Boxing Hall of Fame in 1990 and awarded the Presidential Medal of Freedom in 2005[4]. Ali passed away in 2016 due to complications from Parkinson's disease, but his legacy endures as a symbol of courage, resilience, and social justice[4][5].