Marcos René Maidana (born July 17, 1983) is an Argentine former professional boxer who competed from 2004 to 2014. He held world championships in two weight classes, including the WBA (Regular) super lightweight title from 2011 to 2012 and the WBA welterweight title from 2013 to 2014.
Maidana began his career in his native Argentina, winning his first 25 fights with 24 stoppages. He suffered his first loss in a controversial split decision against Andreas Kotelnik for the WBA super lightweight title in 2009.
In June 2009, Maidana made his U.S. debut against Victor Ortiz, winning by TKO in the sixth round to claim the interim WBA super lightweight title. He successfully defended the title against DeMarcus Corley and Victor Cayo before facing Amir Khan in a unification bout in December 2010, losing by unanimous decision in a closely contested fight.
Maidana moved up to welterweight in 2012, losing to Devon Alexander in his debut at the weight. He rebounded with victories over Jesus Soto Karass and Josesito Lopez before facing Adrien Broner for the WBA welterweight title in December 2013. Maidana scored a surprise unanimous decision victory, handing Broner his first professional loss.
In May 2014, Maidana faced Floyd Mayweather Jr. in a unification bout, losing by majority decision in a competitive fight. The rematch occurred in September 2014, with Mayweather winning unanimously.
Maidana announced his retirement from professional boxing in August 2016 at the age of 33. He finished with a record of 35 wins (31 by knockout) and five losses. Known for his formidable punching power and aggressive style, Maidana was never stopped in any of his five defeats.