Marvelous Marvin Hagler ruled over the middleweight division with an iron fist for much of the 1980s before his reign was ended by Sugar Ray Leonard in one of the most controversial judging decisions of all time.
Hagler, who has died suddenly aged 66, made 12 successful defences of the crown he had long coveted, the high point of which was indisputably getting the better of Thomas Hearns in an eight-minute firefight known as 'The War'.
It was the penultimate win of a 67-fight professional career that ended after his defeat to Leonard, who came out of retirement in April 1987 to upset the odds at Caesars Palace in Las Vegas in a bout that still divides opinion.
Many favoured Hagler's aggression but he was ultimately outfoxed by a slippery Leonard, who flicked out the jab and landed flurries towards the end of most rounds that, while not particularly harmful, would catch the judges' eyes.
A split-decision loss disgusted Hagler, who retired 14 months later at the age of 34 with a record of 62 wins - 52 by knockout - three defeats and two draws after becoming "tired of waiting" for Leonard to decide on a rematch.
By that stage, though, Hagler had already cemented his status as one of the all-time greats and the tangles he, Leonard, Hearns and Roberto Duran had with each other in the '80s would see them chronicled as the 'Four Kings'.
Hagler did it the hard way
He arguably had the toughest road to prominence. He was born on May 23, 1954, in Newark, New Jersey, as the oldest of six children to Ida Mae Hagler and Robert Sims, who abandoned the family when Marvin was a child.
Ida Mae therefore raised Hagler, his brother and their four sisters, eventually uprooting the family following the 1967 Newark riots to Brockton, Massachusetts, where the eldest child would discover a penchant for boxing.
He was discovered as an amateur by the Petronelli brothers, Goody and Pat, who operated a gym in the city and went on to train Hagler for the entirety of his career in the paid ranks.
Hagler often considered himself something of a loner – he once remarked that wounded birds in his mother's backyard were "the only friends I could relate to, maybe the only friends I really liked. I was always by myself".
That feeling of being a pariah followed him in boxing, where he avenged contended losses to Bobby Watts and Willie Monroe before being granted a shot at the undisputed middleweight title held by Alan Minter in September 1980.
Ten months earlier, the suspicion Hagler had of being treated unfairly intensified after his contest against Vito Antuofermo was ruled a draw, and so the American left no room for doubt against Minter.
Minter, who defeated Antuofermo twice, was stopped inside three rounds at Wembley Stadium, where violence in the stands after the fight meant Hagler did not have his hand raised after capturing the WBC and WBA titles.
Having taken so long to reach the top of the mountain - the win over Minter was his 54th fight - Hagler was in no hurry to begin the descent, with the rampaging southpaw stopping 11 of his next 12 opponents.
Only the great Duran was able to get to the final bell in 1983 although the Panamanian's two-round capitulation against Hearns the following year meant many thought the 'Hitman' would be able to end Hagler's long rule.
Fight of the Year against Hearns
The 1985 showdown at Caesars Palace lasted three rounds but it was carnage. A gash on Hagler's forehead threatened to end the fight earlier but the champion refused to buckle in a first round that has gone down in boxing folklore.
The pair threw everything at each other and although the blood flowed freely from Hagler's bald head, it was Hearns who blinked first, wilting against the ropes and then floored as his foe rained down rights and lefts.
Hearns rose rubbery-legged and the fight was stopped. While he was the winner, Hagler looked a shadow of himself when he knocked out John Mugabi in 1986, prompting Leonard to come out of a third - of five - retirements.
Leonard would go back into retirement after defeating Hagler, who did not prevaricate when he decided to stop fighting in June 1988, moving to Italy and starring in several films.
Hagler, who legally changed his name to 'Marvelous Marvin Hagler', fathered Charelle, Celeste, James, Marvin Jr, and Gentry with first wife Bertha. He is survived by his second wife Kay and five children.