Marvelous Marvin Hagler, the undisputed middleweight boxing champion between 1980 and 1987, has died. He was 66.

Hagler’s wife Kay shared the news via her husband’s Facebook fan club page. “I am sorry to make a very sad announcement,” she wrote. “Today unfortunately my beloved husband Marvelous Marvin passed away unexpectedly at his home here in New Hampshire. Our family requests that you respect our privacy during this difficult time.”

Born on May 23, 1954 in Newark, New Jersey, Hagler was one of the greatest boxers during a golden era for the sport. From 1973 to 1987, Hagler, standing 5’9,” competed in 67 boxing matches, winning 62 of them and 52 by knockout. It took six years and 50 bouts for the talented southpaw to earn a shot at the World Boxing Association’s middleweight belt. His first attempt to earn the title was in 1979 against Italian Vito Antuofermo. Although Hagler thought he won the match, it ended in a draw.

In 1980, Hagler’s quest for a title continued. He defeated Algerian boxer Loucif Hamani by pummeling him to the ground in the second round. Two months later, Hagler knocked out Bobby Watts in the second round. The next month, he fought Mexican Marcos Geraldo and won by unanimous decision.

On September 27, 1980 after seven years as a professional boxer and 51 fights (with only two losses) to his name, Hagler beat Alan “Boom Boom” Minter at Wembley Arena in London. The bout ended in the third round after Hagler punched open several cuts on Minter’s face. The referee stopped the fight and Minter’s manager agreed his fighter could not continue. At age 26, Hagler was a champion.

For seven consecutive years, Hagler held onto the WBA middleweight title. In 1983, shortly after he changed his first name to his moniker Marvelous, he nabbed the inaugural International Boxing Federation (IBF) belt by knockout in four rounds against Wilford Scypion.

Hagler defended his title 12 times before he faced Sugar Ray Leonard on April 6, 1987 at Caesar’s Palace in Las Vegas, Nevada. The folkloric fight lasted 12 rounds and ended in a split decision with Leonard being named the victor. Many boxing fans still believe the winner of the matchup is debatable. Hagler would retire a year later to pursue acting in Italy.

After dominating for nearly a decade, Hagler was inducted into the International Boxing Hall of Fame in 1993, and is widely considered to be pound-for-pound one of the greatest middleweight boxers to compete in his era. He is survived by his wife and his five children.