Eddie Hearn is the latest to pay tribute to the former undisputed middleweight champion and admitted, there isn't a fighter 'more respected' than Hagler in world boxing.
Hagler, who passed away aged 66, was part of a golden era in the sport alongside Sugar Ray Leonard, Roberto Duran and Thomas Hearns - otherwise known as the Four Kings.
After winning his first world title in 1980, by demolishing Alan Minter, Hagler would dominate the middleweight division and is most remembered for his 1985 Fight of the Year victory over Hearns and a controversial defeat to Leonard.
Promoter Hearn, who delivered a potential 2021 Fight of the Year between Juan Estrada and Roman Gonzalez, spoke to Ak and Barak about the heart and determination of Hagler, who had limited amateur experience.
"There wasn't anyone who was a sports fan who didn't know who Marvin Hagler was," Hearn said.
"The story of Marvin Hagler is that he wasn't supposed to make it. He wasn't supposed to be a Hall of Famer. He wasn't supposed to be a legend of the sport.
"He was just a blue collar guy. He was just a club fighter really. With no massive amateur pedigree or massive aspirations, but just someone that learned how to fight and learned how to win. He had something inside him that was very difficult to beat."
"Hagler was never Sugar Ray Leonard but what he had was he was so tough and so strong.
"He would break you down and he would keep the pressure on, and that's what he done to Tommy Hearns. He broke Tommy Hearns.
"He was someone that loved the sport but didn't feel the need when he left boxing to stay in the sport.
"I liked the way that he lived this really quiet lifestyle. I know he had a house in Italy and he spent a lot of time there. He led a quiet lifestyle. You will struggle to find a fighter who's more respected."