Muhammad Ali, the three-time world heavyweight boxing champion who helped define his turbulent times as the most charismatic and controversial sports figure of the 20th century, died on Friday. He was 74.

His death was confirmed by Bob Gunnell, a family spokesman.

Ali was the most thrilling if not the best heavyweight ever, carrying into the ring a physically lyrical, unorthodox boxing style that fused speed, agility and power more seamlessly than that of any fighter before him.

But he was more than the sum of his athletic gifts. An agile mind, a buoyant personality, a brash self-confidence and an evolving set of personal convictions fostered a magnetism that the ring alone could not contain. He entertained as much with his mouth as with his fists, narrating his life with a patter of inventive doggerel. (“Me! Wheeeeee!”)

Ali was as polarizing a superstar as the sports world has ever produced — both admired and vilified in the 1960s and ’70s for his religious, political and social stances. His refusal to be drafted during the Vietnam War, his rejection of racial integration at the height of the civil rights movement, his conversion from Christianity to Islam and the changing of his “slave” name, Cassius Clay, to one bestowed by the separatist black sect he joined, the Lost-Found Nation of Islam, were perceived as serious threats by the conservative establishment and noble acts of defiance by the liberal opposition.

Loved or hated, he remained for 50 years one of the most recognizable people on the planet.