HW - Joe Louis - 25 Defenses - Lineal/WBA CW - Johnny Nelson - 14 Defenses - WBO LHW - Dariusz Michalczewski - 23 Defenses - WBO SMW - Joe Calzaghe & Sven Ottke - 21 Defenses - WBO & IBF, respectively MW - Bernard Hopkins - 20 Defenses - IBF LMW - Gianfranco Rosi - 11 Defenses - IBF WW - Henry Armstrong - 19 Defenses - Lineal LWW - Julio Cesar Chavez - 11 Defenses - WBC LW - Artur Grigorian - 17 Defenses - WBO SFW - Tod Morgan - 12 Defenses - WBA FW - Eusebio Pedroza - 19 Defenses - WBA SBW - Wilfredo Gomez - 17 Defenses - WBC BW - Orlando Canizales - 16 Defenses - IBF SFW - Khaosai Galaxy - 19 Defenses - WBA FW - Pongsaklek Wonjongkam - 19 Defenses - WBC LFW - Myong Woo-Yuh - 17 Defenses - WBA MW - Ricardo Lopez - 21 Defenses - WBC :bbb
Long ways to go still. Especially if you only count the lineal title. He does have quite a lot with his current IBF belt, though. Some people who pretend he didn't lose the title and that he doesn't have two separate reigns like to include all of his defenses of any belt he's had ever, in which case he would be approaching Louis, but not in any sort of logical reality...
The problem with these lists is that they put guys who hold the whole title up against guys who only hold one minor piece. Ivan Calderon has more defenses of his piece than Carl Monzon had of the whole thing, but the unified title ought to count for three or four defenses each time if you aren't counting the partial titles as fractions. The whole time that Michalczewski had his WBO strap Roy Jones had all the others and was the man in his division. Nobody can say that about Joe Louis and his reign.
Won the IBF belt vs. Byrd in 2006 (also won the vacant IBO belt). Became IBF/WBO champion when he beat Sultan Ibragimov in '08. Became IBF/WBO/WBA champ when he beat Haye in 2011.
