Marvin Hagler is known for his role in the Four Kings era of boxing, defeating Roberto Duran and Thomas Hearns, but it was neither of these wins that made him Marvellous.
Marvin Hagler retired with a record of 62-3-2, and will go down, alongside Sugar Ray Leonard, Roberto Duran, and Thomas Hearns as a King of boxing.
Hagler got his nickname from an announcer at the Golden Gloves tournaments as an amateur but adopted it legally after a fight he had just three years before his unforgettable clash with Hearns.

Marvin Hagler’s marvellous KO turned Caveman opponent to life of crime
In 1982, Hagler fought William ‘Caveman’ Lee, nicknamed as such due to the sideburns he had as a child.
Caveman was a 21-2 knockout artist at the time of his clash with Hagler, who KO’d John Mugabi, but in reality, boxing was never his dream. His father had been into boxing but was disabled in a work accident, forcing Caveman to follow his dreams for him.
Lee, who trained under Emanuel Steward at the Kronk Gym in Detroit, was stopped by Hagler in just 67 seconds, marking a humiliating and devastating defeat for the ‘Caveman’.
Frustrated with the loss, and life in general, Caveman Lee fell into a deep depression and resorted to multiple armed robberies, including a bank robbery. He claimed these were done not for the money, but because he wanted to be jailed or killed.
Lee briefly returned to boxing after his arrest and time served, but soon admitted he didn’t have the passion for it.
Lee said of boxing: “I guess I just didn’t have the heart for it. I don’t know if I ever did. I never liked boxing, I guess it was just something that was drilled into me.”
Tragically he also said: “I don’t know what I would have done in life if I had followed my own dreams. I don’t even know what my dreams were. My pop gave me his dreams.”
Thankfully his life has turned around since then and he now has a job and family.
How Caveman Lee forced Marvin Hagler to change his name to Marvellous
It was the fight with Caveman where ABC-TV told Hagler they would not announce him as ‘Marvellous.’
Frustrated, Hagler pointed to the hypocrisy of referring to William Lee as ‘Caveman’, and of Ray Leonard’s nickname ‘Sugar’.

The network told Hagler, according to BoxRec:
”If he wants to be called Marvelous Marvin at ABC, tell him to go to court and have his name changed.”
That’s exactly what he did, legally changing his name from Marvin Nathaniel Hagler to Marvellous Marvin Hagler.
Hagler lost only to Sugar Ray Leonard, who was retired by Hector Camacho, Willie Monroe, and Bobby Watts. He holds a career-defining win over Roberto Duran, who was KO’d by Thomas Hearns, a man Hagler also defeated.