|Born: November 19, 1974|
Ciudad Obregón, Sonora, Mexico
|MLB: June 15, 1997, for the Chicago White Sox|
|NPB: July 2, 2004, for the Osaka Kintetsu Buffaloes|
|MLB: June 22, 2001, for the Oakland Athletics|
|NPB: August 27, 2004, for the Osaka Kintetsu Buffaloes|
|Runs batted in||21|
Mario Ayelar Valdez (born November 19, 1974) is a Mexican former professional baseball first baseman. He played during three Major League Baseball (MLB) seasons for the Chicago White Sox and Oakland Athletics. He also played one season in Nippon Professional Baseball (NPB) for the Kintetsu Buffaloes in 2004.
Valdez was drafted by the White Sox in the 48th round of the 1993 amateur draft. Valdez played his first professional season with their Class A (Short Season) Utica Blue Sox in 1986, and his last season with the independent Pensacola Central of the Central League, in 2004. His last affiliated season was in 2003, when he played for the San Diego Padres' Triple-A unit, the Portland Beavers.
Valdez played with Mexican team Tomateros de Culiacan in winter ball in La Liga Mexicana del Pacifico. He debuted in 1995 with the team which won the championship the same year, also playing in 1996-1997, 2001-2002, 2003–2004 and the Caribbean Series in 1996-2002.