is an Argentine former professional footballer who played as an attacking midfielder.

From 2013 to 2021, Valeri played for Major League Soccer club Portland Timbers, and is regarded as one of the league's greatest players of all time, as well as the greatest player in Portland Timbers history. Valeri was named the MLS Cup Most Valuable Player after he led the Timbers to win MLS Cup 2015. He was later presented as the MLS MVP following his career-setting 2017 season. While in Major League Soccer, Valeri was selected into the MLS All-Star team four times and was included three times in the MLS Best XI.

Valeri began his career with his boyhood club Lanús. Promoted to the first team by head coach Miguel Ángel Brindisi, Valeri made his Primera División debut in September 2003 against Vélez Sarsfield. He soon broke into the starting line-up more consistently, having his breakout season in 2007–08, helping Lanús to the Torneo Apertura title. In 2009, Valeri joined Portuguese club Porto on loan for the 2009–10 season, helping the club win the Taça de Portugal. The next season, Valeri was loaned out to Spanish club Almería, where his loan was eventually ended early in December 2010.

In August 2012, Valeri and his family were victims in an armed robbery in Lanús. The incident lead to Valeri instructing his agent to pursue a move abroad more aggressively. In January 2013, Valeri joined the Portland Timbers on loan for the 2013 season. The deal was eventually made permanent in August 2013. In his debut season, Valeri helped the club top the Western Conference standings, earning him the MLS Newcomer of the Year award. In December 2015, he scored the opening goal for the Timbers' after 27 seconds against the Columbus Crew in MLS Cup 2015. The fastest goal in MLS Cup history, the Timbers would go on to defeat the Crew and win their first ever championship. Two seasons later, Valeri registered his best season statistically, posting a career-high 21 goals while recording 11 assists. He helped the Timbers top the Western Conference standings and won the MLS Most Valuable Player award. The following season, Valeri helped lead his side to MLS Cup 2018 against Atlanta United FC, where they were defeated 0–2. In August 2020, Valeri helped captain the Timbers to the final of the MLS is Back Tournament, defeating Orlando City SC.

Valeri is the all-time leading goalscorer for the Portland Timbers with 100 goals in all competitions. He is the 14th all-time top scorer and is 10th all-time in assists in Major League Soccer history.

Valeri earned three caps for Argentina, all occurring in 2011. He made his international debut for his country on 16 March against Venezuela as Argentina won 4–1.