Muhammad Ali, born Cassius Marcellus Clay Jr., was an American professional boxer, philanthropist, and social activist. He is widely considered one of the greatest boxers of all time. Ali became an Olympic gold medalist and the world heavyweight champion, known for his footwork, speed, and powerful punches. Outside the ring, he was known for his charismatic personality, controversial political views, and his refusal to be drafted into the Vietnam War. Ali's legacy extends beyond boxing, as he used his fame to advocate for civil rights, racial justice, and humanitarian causes.