Muhammad Ali was an American professional boxer, activist, and philanthropist. Nicknamed "The Greatest", he is widely regarded as one of the most significant and celebrated sports figures of the 20th century and as one of the greatest boxers of all time.
Ali was born and raised in Louisville, Kentucky, and began training as an amateur boxer at age 12. At 18, he won a gold medal in the light heavyweight division at the 1960 Summer Olympics, and turned professional later that year. He converted to Islam and became a Muslim after 1961, and eventually took the name Muhammad Ali. He won the world heavyweight championship from Sonny Liston in a major upset at age 22 in 1964. In 1966, Ali refused to be drafted into the military, citing his religious beliefs and opposition to the Vietnam War. He was arrested, found guilty of draft evasion, and stripped of his boxing titles. He appealed the decision to the Supreme Court, which overturned his conviction in 1971, but he had not fought for nearly four years and lost a period of peak performance as an athlete.