commonly known as Nelson Valdez or Nelson Haedo in Spanish speaking countries, is a Paraguayan professional football coach and a former player who played as a striker for clubs in Paraguay, Germany, Spain, Russia, the United Arab Emirates, Greece, the US and for the Paraguay national team between 2000 and 2021. He is an assistant coach with the German club Werder Bremen II.

Valdez started his career with Atlético Tembetary, progressing through their youth system to the first-team squad where he made his debut at the age of 16 in Paraguayan División Intermedia in 2000. He finished his career with the club having scored 11 goals in 22 league appearances. In 2001, he was scouted to Germany's Werder Bremen II, where he scored 15 goals in 30 Regionalliga Nord appearances in his second season before joining the club's first-team. In 2003, Valdez was selected for the Paraguay under-20 national team where he scored one goal in four appearances at the 2003 FIFA World Youth Championship. In his second season with Werder Bremen, he claimed the 2003–04 Bundesliga and 2003–04 DFB-Pokal, having scored five goals in 21 league appearances that season. Valdez debuted in the 2004–05 UEFA Champions League on 14 September 2004 and scored his first two Champions League goals in a 2–0 victory against Valencia in December. During his years at Werder Bremen, Valdez had his appearances limited due to competition from teammates Aílton, Angelos Charisteas and both Miroslav Klose and Ivan Klasnić, who were the Bundesliga's top striking duo at the time.

Valdez left Werder Bremen in August 2006 to join fellow Bundesliga side Borussia Dortmund for a fee of €4.7 million on a four-year contract, where he was given the number 9 shirt. Within those four years, he scored 16 goals in 113 Bundesliga appearances and helped Dortmund qualify for the 2010–11 UEFA Europa League. After an impressive performance at the 2010 FIFA World Cup with Paraguay, Valdez joined La Liga side Hércules for €3.5 million on a three-year contract, where he partnered with French striker David Trezeguet. He became the most expensive signing in the club's history and scored a double on his debut in a 2–0 win at the Camp Nou against Barcelona on 11 September. After eight goals in 25 league appearances in the 2010–11 La Liga season, Hércules were relegated to the Segunda División and Valdez was then transferred to Russian Premier League side Rubin Kazan for €4 million. Valdez was later loaned out to Valencia and went on to enjoy stints with Al Jazira and Olympiacos. In July 2014, Valdez returned to the Bundesliga and signed with Eintracht Frankfurt, being reunited with former Werder Bremen coach Thomas Schaaf. Valdez played from 2015 to 2016 with American club Seattle Sounders FC in Major League Soccer, scoring in the playoffs and winning the MLS Cup in his final season.

Valdez has represented Paraguay at the 2006 and 2010 FIFA World Cup tournaments, he also participated at the 2004, 2011 and 2015 Copa América tournaments; in 2011 Paraguay finished runners-up. Valdez has made over 70 national team appearances and scored 13 goals, with one of his goals coming in a 1–0 historic victory against rivals Argentina on 9 September 2009 which secured Paraguay's qualification to the 2010 World Cup and the result being Paraguay's second official victory against Argentina.