This is what we found on Wikipedia regarding the Championship Boxing:

In boxing, the undisputed champion of a weight class is the boxer who simultaneously holds world titles from all major organizations recognized by each other and the International Boxing Hall of Fame. There are currently four major sanctioning bodies: WBA, WBC, WBO, and IBF. There were many undisputed champions before the number of major sanctioning bodies recognizing each other increased to four in 2007, but there have been only 24 boxers (11 male and 13 female) to hold all four titles simultaneously.