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One of the toughest and most beloved boxers of the modern era, former undisputed middleweight champion Marvelous Marvin Hagler died Saturday at age 66. 

Hagler's wife, Kay, confirmed the news with a post on her late husband's Facebook fan page although no official cause of death was given. 

"I am sorry to make a very sad announcement," the social media post read. "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. With love, Kay G. Hagler."

Promoter Bob Arum and Top Rank later confirmed the news in a press release.

"Marvelous Marvin Hagler was among the greatest athletes that Top Rank ever promoted. He was a man of honor and a man of his word, and he performed in the ring with unparalleled determination. He was a true athlete and a true man. I will miss him greatly," Arum said.

A 1993 inductee to the International Boxing Hall of Fame, Hagler made 12 defenses of the undisputed middleweight title he held from 1980 to 1987. The native of Newark, New Jersey, who settled in Brockton, Massachusetts, as a teenager, went on to take part in a pair of the most memorable fights in the sport's history. 

Hagler (62-3-2, 52 KOs), a southpaw who switched stances with ease, stopped Thomas Hearns in the third round of their 1985 middleweight title bout known today simply as "The War." The fight was instantly hailed as one of the most exciting, violent and dramatic title fights boxing has ever produced. 

The final bout of Hagler's 67-bout professional career remains nearly as memorable as the reigning 160-pound champion finally secured a fight against longtime rival Sugar Ray Leonard in 1987. The 12-round thriller, which Leonard won by split decision, remains one of the most disputed results to date.

Disgusted about the scoring in the Leonard fight, Hagler would never fight again and retired the following year at the age of 34. Hagler immediately moved to Italy, where he spent much of his life after boxing, and pursued an acting career. 

A true fighter's fighter thanks to his ability to box just as good as he punched, Hagler's calling card throughout a career that began when he turned pro in 1973 was his chin. Not only was Hagler never stopped in any of his three defeats, he was knocked down just once against Juan Roldan in 1984, which Hagler immediately disputed should have been called a slip. 

A member of the famed "Four Kings" of the 1980s -- a celebrated group of Hall of Fame middleweights that included Hearns, Leonard and Roberto Duran -- Hagler also owned a decision win against Duran in 1983. 

Hagler went 55-1 as an amateur, including winning the United States National Championship at middleweight in 1973. But he chose to turn pro rather than seek Olympic fame and was forced to take the long road toward gaining respect and riches by being forced to repeatedly prove himself inside the ring. 

The fact that Hagler wasn't as celebrated as his rival Leonard, who won Olympic gold in 1976, helped build a resolve that only made him tougher. Hagler's first shot at the middleweight title also ended in disputed fashion when he claimed robbery after settling for a split draw against Vito Antuofermo in 1979. 

One year later, Hagler would finally have his moment when he traveled to London in 1980 to claim the undisputed middleweight championship by stopping Alan Minter. The celebration proved short lived, however, as Hagler was pelted with trash and debris by the partisan crowd. 

Hagler went on to earn Fighter of the Year honors in 1983 and 1985 by the Boxing Writers Association of America. He was also named Fighter of the Decade in the 1980s by Boxing Illustrated. 

A father of five children with his first wife, Bertha, Hagler was also the half-brother of former middleweight boxer Robbie Sims. 

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