Boxer Record Weight class Title (s) Championship years Title defenses Notes Jimmy Barry 59 -- 0 -- 9 (2) Bantamweight World 1894 -- 1899 6 (3 draws) Joe Calzaghe 46 -- 0 -- 0 (0) Super middleweight WBO 1997 -- 2008 21 Vacated title to move up to light heavyweight. IBF 2006 Vacated title to fight Peter Manfredo Jr. instead of # 1 contender Robert Stieglitz. The Ring, lineal 2006 -- 2008 Vacated titles to move up to light heavyweight. WBA, WBC 2007 -- 2008 0 Light heavyweight The Ring 2008 Retired and vacated title. Kim Ji - won 16 -- 0 -- 2 (0) Super bantamweight IBF 1985 -- 1986 Mihai Leu 28 -- 0 -- 0 (0) Welterweight WBO Forced to retire from boxing due to an injury. Ricardo López 51 -- 0 -- 1 (0) Minimumweight WBC 1990 -- 1998 22 Vacated title to move up to light flyweight. WBO 1997 -- 1998 0 Unified WBC and WBO titles. Stripped of WBO title for saying he wanted to give the belt to his father. WBA 1998 0 Vacated title to move up to junior flyweight. Light flyweight IBF 1999 -- 2002 Rocky Marciano 49 -- 0 -- 0 (0) Heavyweight World 1952 -- 1956 6 Terry Marsh 26 -- 0 -- 1 (0) Light welterweight IBF Forced to retire due to epilepsy. Floyd Mayweather Jr. 50 -- 0 -- 0 (0) Super featherweight WBC 1998 -- 2002 8 Vacated title to move up to lightweight. Lightweight WBC 2002 -- 2004 Vacated title to move up to light welterweight. Light welterweight WBC 2005 -- 2006 0 Vacated title to move up to welterweight. Welterweight WBA, WBC 2006 -- 2008, 2011 -- 2015 8 Retired at 49 -- 0 in 2015; returned in 2017 for non-title McGregor fight and then retired again. Light middleweight WBA, WBC 2007, 2012 -- 2015, 2017 Jack McAuliffe 30 -- 0 -- 5 (1) Lightweight World 1886 -- 1893 7 -- 0 -- 2 (0) Sven Ottke 34 -- 0 -- 0 (0) Super middleweight IBF 1998 -- 2004 21 WBA 2003 -- 2004 Defended IBF title and defeated WBA champion to become WBA Super champion. Dmitry Pirog 20 -- 0 -- 0 (0) Middleweight WBO 2010 -- 2012 Forced to retire from boxing due to chronic back injuries. Harry Simon 30 -- 0 -- 0 (0) Light middleweight WBO 1998 -- 2001 Vacated title to move up to middleweight. Middleweight WBO 2002 0 Won WBO interim middleweight title in 2001 and the outright title in 2002. Stripped of title at 29 -- 0 when he was unable to defend it due to injuries suffered in a car crash. Had one more non-title fight before retiring. Pichit Sitbangprachan 24 -- 0 -- 0 (0) Flyweight IBF 1992 -- 1994 Retired at 21 -- 0 and then made a comeback. Edwin Valero 27 -- 0 -- 0 (0) Super featherweight WBA 2006 -- 2008 Vacated title to move up to lightweight. Lightweight WBC 2009 -- 2010 Vacated title to move up to light welterweight. Committed suicide after allegedly killing his wife in 2010. All 27 fights were knockout wins. Andre Ward 32 -- 0 -- 0 (0) Super middleweight WBA 2009 -- 2015 6 Vacated titles in 2015 to move up to light heavyweight. WBC, The Ring, lineal 2011 -- 2015 1 (WBC), 2 (The Ring, lineal) Light heavyweight WBA, WBO, The Ring, lineal 2016 -- 2017 1 (WBA, IBF, WBO), 0 (The Ring, lineal)
who has the most undefeated wins in boxing
Jimmy Barry