Marvelous Marvin Hagler, the middleweight legend and one of the greatest fighters in boxing history, died on Saturday in New Hampshire. He was 66.

Hagler’s death was announced on the verified Marvelous Marvin Hagler Facebook Fan Club page with a message from Hagler’s wife, Kay G. Hagler.

“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.”

One of Hagler’s sons, James, told TMZ that his father was taken to the hospital earlier on Saturday after experiencing breathing problems and chest pains.

Hagler, who boxed from 1973 to 1987 and was one of the famed round-robin of fights among the “Four Kings” of the 1980s along with Sugar Ray Leonard, Thomas Hearns and Roberto Duran, took years to make his name because nobody would give him a chance to fight for a middleweight world title until he was deep into his career.

He was 46-2-1 when he finally got a shot against undisputed 160-pound champion Vito Antuofermo in Las Vegas on Nov. 30, 1979 on ABC in prime time on the undercard of when Leonard stopped Wilfred Benitez in the 15th round to win the WBC welterweight crown. Hagler was held to a highly controversial draw.

Four fights later, Hagler got a second title shot, traveling to London and knocking out Alan Minter in the third round to win the undisputed title. The result so enraged Minter’s British fans that they pelted the ring with debris and prevented Hagler from receiving his belt in the ring and forced him to rush to the dressing room, which Hagler always resented.

But Hagler (63-3-2, 52 KOs), managed and trained by brothers Goody and Pat Petronelli, would hold the title with a vice-like grip for the next seven years, making 12 consecutive successful defenses before losing it by split decision to Leonard on April 6, 1987 in one of the biggest fights and most controversial decisions in boxing history.

There was talk of a rematch but Hagler was so upset by the decision in the fight that he never fought again. He retired to the easy life and became an actor in various films in Italy, where he also lived.

As big as the fight with Leonard was, he was best known for his epic showdown with Hearns, the former welterweight champion and reigning junior middleweight champion, who moved up in weight to challenge Hagler for his title on April 15, 1985 at the famed outdoor area at Caesars Palace in Las Vegas.

They charged at each other at the opening bell and produced a breathtaking slugfest many regard as the greatest fight in boxing history. Bleeding badly, Hagler knocked Hearns out in the third round in his greatest triumph, one that shot him to super stardom.

Hagler, a southpaw with tremendous punching power immediately recognizable by his shaved head, also outpointed Duran in 1983 and defeated Antuofermo in a rematch, Juan Domingo Roldan, Mustafa Hamsho (twice) and John “The Beast” Mugabi in title defenses.

“As far as I’m concerned the best middleweight of the 55 years I’ve been in boxing,” Top Rank promoter Bob Arum, who promoted all of Hagler’s fights from mid-1979 to the end of his career and remained friendly with him after his retirement. “I can’t compare him to (Harry) Greb and Sugar Ray Robinson. Those guys were before my time. The only one I would maybe hesitate would be (Carlos) Monzon. But Hagler’s the best middleweight and one of the best fighters I’ve ever promoted.”

Hagler was born in Newark, New Jersey, on May 3, 1954 and moved to Brockton, Massachusetts, in the late 1960s. Before finally getting a middleweight title shot – he never fought in any other division – Hagler made his bones fighting several contenders in Philadelphia, such as Bobby “Boogaloo” Watts, Willie “The Worm” Monroe, Eugene “Cyclone” Hart and Bennie Briscoe before linking up with Arum in mid-1979.

Hagler was inducted into the International Boxing Hall of Fame 1993

“Marvelous Marvin Hagler was among the greatest athletes that Top Rank ever promoted,” Arum said. “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.”

Dan Rafael was's senior boxing writer for fifteen years, and covered the sport for five years at USA Today. He was the 2013 BWAA Nat Fleischer Award winner for excellence in boxing journalism.