Ali reunited the belts by beating WBA champion Ernie Terrell on February 6, 1967. He was stripped of the WBA belt on April 28, 1967 for refusing induction into the United States army, but retained recognition by the WBC until February 16, 1970.
Lennox Lewis became undisputed champion by defeating Evander Holyfield, successfully unifiying his WBC belt with Holyfield's WBA and IBF belts. With that victory, he was also awarded the vacant IBO title. Lewis was stripped of his WBA belt due to a contract dispute regarding a clause in the 2nd Holyfield contract which stipulated he must fight the WBA number 1 contender next. The number 1 contender at that time was Henry Akinwande but he was ill so John Ruiz was later moved up to number 1. The WBA gave Lewis permission under these circumstances to fight WBC ranked contender Michael Grant next as long as he agreed to fight Ruiz in the following bout. Lewis agreed but Ruiz's promoter challenged the WBA's decision in court.
Evander Holyfield became the first undisputed Cruiserweight Champion by defeating Carlos De León, to unify his WBA and IBF belts with De Leon's WBC belt. He relinquished all the belts after moving up to the Heavyweight division. The Ring Magazine stopped recognizing the weight class in 1987.
Whilst Dariusz Michalczewski was the Lineal/WBO champion, Roy Jones Jr. defeated Reggie Johnson for his IBF belt, successfully unifying with his WBA and WBC belts. Jones relinquished his titles after he moved to the heavyweight division.
To date, there have been no undisputed super middleweight champions. The closest the division came to having an undisputed champion was on November 3, 2007, when Joe Calzaghe defeated Mikkel Kessler to unify the WBA (Super), WBC and WBO titles; however, the IBF champion at the time was Lucian Bute.
Hagler was recognized as the inaugural IBF champion, adding the belt to his undisputed status. He lost the IBF and WBA belt recognitions after deciding to fight Sugar Ray Leonard. He lost the WBC belt after losing to Leonard.
Bernard Hopkins became the undisputed champion after defeating Félix Trinidad in a Middleweight tournament to successfully unify the WBC WBA and IBF belts. He later added the WBO to his undisputed status after defeating Oscar De La Hoya, becoming the first man to ever hold all four titles simultaneously.
Taylor lost his IBF belt for taking a rematch against Hopkins instead of fighting the IBF #1 challenger Arthur Abraham. He officially lost his undisputed status after being stripped of his WBA belt on December 14, 2006
Winky Wright became the first undisputed champion of the light middleweight division after unifying his IBF belt with Shane Mosley's WBA and WBC belts. Wright lost the IBF belt for taking a rematch against Mosley.
Sugar Ray Leonard unified his WBC with Thomas Hearns's WBA to become the first undisputed champ in seven years. Leonard later relinquished the title after retiring from boxing because of a detached retina.
Judah lost his undisputed championship to Carlos Baldomir, but despite being recognized as the "true" welterweight champion, Baldomir did not pay the sanctioning fees for the WBA or IBF. Consequently, the WBA relinquished Judah as its champion, while the IBF continued to recognise him. Judah later lost the IBF title to Floyd Mayweather, Jr.
Kostya Tszyu became the undisputed Junior Welterweight champ after defeating Zab Judah to successfully unify his WBA and WBC belt with Judah's IBF belt. Tszyu was stripped of the WBA and WBC titles because of extended inactivity due to training injuries and lost his IBF belt to Ricky Hatton.