is a Mexican football coach and former player who played as a defender. He is currently the assistant coach of the Mexico national team. Nicknamed El Káiser, he is regarded as the best defender in Mexico's history and one of the best Mexican players of all time.

Márquez began his career with Atlas in 1996, playing in over 70 games with the club before moving to France in 1999 with Monaco, where he won a Ligue 1 title. In 2003, Márquez joined Barcelona, becoming the first ever Mexican to represent the club. He would go on to play in over 240 games during seven seasons with the Blaugrana and win numerous honors, including four La Liga titles and two UEFA Champions League titles. In 2006, he became the first Mexican player to win the Champions League when Barcelona defeated Arsenal in the final. In 2010, Márquez joined Major League Soccer club New York Red Bulls. After being released from the club in 2012, he returned to his native Mexico, this time to play for León, captaining the team to back-to-back Liga MX titles in 2013 and 2014. Márquez then transferred to Hellas Verona of the Italian Serie A. He returned to his boyhood club Atlas in 2015, and announced his retirement from football in April 2018.

Márquez is the fourth most-capped player in the history of the Mexico national football team, earning 147 caps throughout his career. In 2018, he became only the fourth player to play for his national team in five consecutive editions of the FIFA World Cup, alongside compatriot Antonio Carbajal, Lothar Matthäus, and Gianluigi Buffon, appearing in the 2002, 2006, 2010, 2014, and 2018 tournaments. He is also the Mexican player with the most World Cup matches played with 19. With the national team, Márquez won the 1999 FIFA Confederations Cup, and the 2003 and 2011 editions of the CONCACAF Gold Cup.