List of undefeated boxing world champions
This is a list of world champions in professional boxing who retired undefeated, either during or after a title reign(s). It excludes current titleholders.

List of undefeated boxing world champions

Section Title:
Table Section Text: This is a list of world champions in professional boxing who retired undefeated, either during or after a title reign(s). It excludes current titleholders.

Boxer	Record	Weight class	Title(s)	Championship years	Title defenses	Notes

United States Jimmy Barry	59–0–9 (2)	Bantamweight	World	1894–1899	6 (3 draws)

United Kingdom Joe Calzaghe	46–0–0 (0)	Super middleweight	WBO	1997–2008	21	Vacated title to move up to light heavyweight.

IBF	2006	1	Vacated title to fight Peter Manfredo Jr. instead of #1 contender Robert Stieglitz.

The Ring, lineal	2006–2008	3	Vacated titles to move up to light heavyweight.

WBA, WBC	2007–2008	0

Light heavyweight	The Ring	2008	1	Retired and vacated title.

South Korea Kim Ji-won	16–0–2 (0)	Super bantamweight	IBF	1985–1986	4

Romania Mihai Leu	28–0–0 (0)	Welterweight	WBO	1997	1	Retired from boxing due to an injury.

Mexico 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	2

United States Rocky Marciano	49–0–0 (0)	Heavyweight	World	1952–1956	6

United Kingdom Terry Marsh	26–0–1 (0)	Light welterweight	IBF	1987	1	Retired from boxing due to epilepsy.

United States Floyd Mayweather Jr.	50–0–0 (0)	Super featherweight	WBC	1998–2002	8	Vacated title to move up to lightweight.

Lightweight	WBC	2002–2004	3	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	2

Republic of Ireland Jack McAuliffe	30–0–5 (1)	Lightweight	World	1886–1893	7–0–2 (0)

Germany Sven Ottke	34–0–0 (0)	Super middleweight	IBF	1998–2004	21

WBA	2003–2004	4	Defended IBF title and defeated WBA champion to become WBA Super champion.

Russia Dmitry Pirog	20–0–0 (0)	Middleweight	WBO	2010–2012	3	Retired from boxing due to chronic back injuries.

Namibia Harry Simon	31–0–0 (0)	Light middleweight	WBO	1998–2001	4	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 22–0 when he was unable to defend it due to injuries suffered in a car crash.

Thailand Pichit Sitbangprachan	24–0–0 (0)	Flyweight	IBF	1992–1994	5	Retired at 21–0 and then made a comeback.

Venezuela Edwin Valero	27–0–0 (0)	Super featherweight	WBA	2006–2008	4	Vacated title to move up to lightweight.

Lightweight	WBC	2009–2010	2	Vacated title to move up to light welterweight. Committed suicide after allegedly killing his wife in 2010.

United States 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)

Sentence(s)

Harry Simon is a Namibian undefeated professional boxer.

final_sentence: Harry Simon is a Namibian undefeated professional boxer.