Julio César Chávez González, also known as Julio César Chávez Sr., is a Mexican former professional boxer who competed from 1980 to 2005. A multiple-time world champion in three weight divisions, Chávez was listed by The Ring magazine as the world's best boxer, pound for pound, from 1990 to 1993. During his career he held the WBC super featherweight title from 1984 to 1987, the WBA and WBC lightweight titles between 1987 and 1989, the WBC light welterweight title twice between 1989 and 1996, and the IBF light welterweight title from 1990 to 1991. He also held the Ring magazine and lineal lightweight titles from 1988 to 1989, and the lineal light welterweight title twice between 1990 and 1996. Chávez was named Fighter of the Year for 1987 and 1990 by the Boxing Writers Association of America and The Ring respectively.
Juan Laporte, also known as Juan La Porte is a former boxer who was born in Guayama, Puerto Rico. In 1982, La Porte won the vacant WBC featherweight title, forcing undefeated Colombian Mario "Martillo" Miranda to quit on his stool. Throughout his 22-year-long career, La Porte fought some of the greatest fighters of each decade, including Hall of Fame members Salvador Sanchez, Eusebio Pedroza, Azumah Nelson, Wilfredo Gomez, Barry McGuigan, Kostya Tszyu & Julio Cesar Chavez Sr. He retired in 1999 with a record of 40–16, with many of his losses being highly competitive, and sometimes controversial, affairs.
Carlos Zárate Serna is a Mexican former professional boxer who competed from 1970 to 1988, and held the WBC bantamweight title from 1976 to 1979.
Marco Antonio Barrera Tapia is a Mexican former professional boxer who competed from 1989 to 2011. He held multiple world championships in three weight classes between 1995 and 2007, from super bantamweight to super featherweight.
Anthony "The Bullet" Bonsante is a professional boxer and competitor on reality TV show The Contender. He also works overnight as a supervisor at a distribution center.
Alfonso Salvador Gómez Becerra, better known as Alfonso Gómez, is a Mexican former professional boxer. Gomez is best known for being a competitor on the debut season of reality TV show The Contender, where he finished third out of sixteen fighters and instantly became a fan favorite. Gómez holds notable victories over former world champions Arturo Gatti, Jose Luis Castillo, and Peter Manfredo Jr. He has also fought household names such as Saul Álvarez, Miguel Cotto in a WBO world championship fight, and Shawn Porter.
Ishé Oluwa Kamau Ali Smith is an American former professional boxer who competed from 2000 to 2019. He held the IBF junior middleweight title in 2013, and is the first boxer from Las Vegas to become a professional world champion. During his early career, he participated in the first season of the reality TV show The Contender in 2005.
Tarick Salmaci is a Lebanese-American former professional boxer and North American Boxing Organization (NABO) middleweight champion. He was one of 16 boxers chosen worldwide to participate on season 1 of NBC's reality television series The Contender.
Jimmy Lange is an American professional boxer.
Juan Manuel Márquez Méndez is a Mexican former professional boxer who competed from 1993 to 2014. He is the third Mexican boxer to become a world champion in four weight classes, having held nine world major titles from featherweight to light welterweight, including the lineal championship at lightweight.
José Luis Castillo is a Mexican former professional boxer who competed from 1990 to 2014. Generally considered one of the best lightweights of his era, he is a two-time world champion at that weight, having held the WBC title twice, from 2000 to 2002 and 2004 to 2005; and the Ring magazine and lineal titles from 2004 to 2005. Castillo is best known for his 2005 fight against Diego Corrales, for which he received Fight of the Year awards by both The Ring and the Boxing Writers Association of America, as well as his much-debated first fight with Floyd Mayweather Jr..
Freddy Curiel is an American professional boxer. Curiel was born in La Vega, Dominican Republic and was a contestant on the ESPN reality show, Contender Season 2.
Robert Joseph Guerrero is an American professional boxer. He has held world championships in two weight classes, including the IBF featherweight title twice between 2006 and 2008, and the IBF junior lightweight title from 2009 to 2010. Additionally he has held multiple interim titles at lightweight and welterweight.
Zou Shiming is a Chinese former professional boxer who competed from 2013 to 2017 and held the WBO flyweight title from 2016 to 2017. As an amateur, Zou is China's most successful boxer of all time. In the light-flyweight division, he won three consecutive Olympic medals, as well as three World Amateur Boxing Championships gold medals in 2005, 2007 and 2011.
Geronimo "Gerry" J. Peñalosa is a Filipino former professional boxer who competed from 1989 to 2010. He is a two-weight world champion, having held the WBC super-flyweight title from 1997 to 1998, and the WBO bantamweight title from 2007 to 2009. Originally from the city of San Carlos, Negros Occidental, Peñalosa currently resides in Manila. He was trained mainly by Freddie Roach, and went on to become a boxing trainer himself after retirement. Peñalosa's older brother, Dodie Boy Peñalosa, is also a former boxer and world champion.
Mike Alvarado is an American professional boxer who held the WBO light welterweight title in 2013.
James Micheal de la Rosa is a Mexican professional boxer. He is currently signed with Don King..
Oba Diallo Carr is an American former professional boxer. A product of trainer Emanuel Steward's Kronk Gym in Detroit, he fought three times unsuccessfully for a welterweight world title.
Austin Dwayne Trout is an American professional boxer and bare-knuckle fighter. In boxing he held the World Boxing Association (WBA) light middleweight title from 2011 to 2013.
The Contender 1 is the first season of The Contender.
Jas Phipps
Anatoli Muratov
Fernando Vela
Nurhan Suleymanoglu 
Tarick Salmaci