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.

CBS