Muhammad Ali (/ɑːˈliː/; born Cassius Marcellus Clay, Jr., January 17, 1942 – June 3, 2016) was an American professional boxer, generally regarded as the most significant heavyweight in the history of the sport. Early in his career, Ali was known for being an inspiring, controversial and polarizing figure both inside and outside the boxing ring.[6][7] He is known as one of the most recognized sports figures of the past 100 years, crowned "Sportsman of the Century" by Sports Illustrated and "Sports Personality of the Century" by the BBC.[8] He also wrote several best-selling books about his career, including The Greatest: My Own Story and The Soul of a Butterfly.