Trevor Berbick, the last boxer to fight Muhammad Ali, has been killed in Jamaica by an assailant wielding a hatchet or machete, police said.
Berbick weighs in ahead of his 1986 fight against Mike Tyson
Aged 51 or 52 - his birthdate was disputed - he was found in his native Norwich, 90 miles (145km) east of Kingston, with gaping head wounds.
Police are treating Berbick's death as murder.
Berbick beat Ali in 1981 and briefly held the WBC heavyweight title in 1986 before losing to Mike Tyson.
The former boxer was found near a church with chop wounds and was pronounced dead after being taken to hospital, police said.
No other details were given.
Berbick represented Jamaica at the 1976 Olympic Games in Montreal, losing to the eventual silver medallist.
He opted to stay in Montreal and fight professionally out of Canada.
A promising and powerful heavyweight, he won his first 11 bouts before losing to another rising talent Bernardo Mercado in 1979.
Legally, I'm a spirit - I have no age
He bounced back from that defeat to secure a world title shot against Larry Holmes in April 1981. He lost that fight to a unanimous decision after 15 rounds.
After beating a jaded Ali over 10 rounds in the Bahamas in December 1981, Berbick moved to Florida and signed up with promoter Don King.
606 COMMENT: Give your tributes to Berbick
Nearly five years after his defeat to Holmes, Berbick, who claimed as a teenager to have had a vision of God, upset Pinklon Thomas to win the WBC version of the heavyweight belt.
But his reign lasted only eight months as he lost his first defence to the 20-year-old Tyson when he was stopped in the second round.
He never quite recovered from that defeat, although he continued boxing for another 14 years, and his later career saw him combine arrests with bizarre episodes such as fighting Japanese sumo wrestler Nobuhiko Takada in a 1991 TV stunt.
Berbick's jabs finally ended Ali's long career in the ring
His boxing licence was eventually revoked in 2000 when a CAT scan following his a 12-round win over Canadian Shane Sutcliffe revealed a blood clot on his brain.
By that time, however, he had already been ordered out of the US for violating his parole following a conviction for sexual assault on a family babysitter. He was again ordered to be deported in 2002.
In spanning the Ali and Tyson eras, Berbick beat such fighters as Iran Barkley, Greg Page and John Tate. Among his losses were those to Buster Douglas, Renaldo Snipes and Larry Holmes.
When asked once about his age, a detail that was never nailed down during his lifetime, Berbick said: "Legally, I'm a spirit. I have no age."