Osmar Mares Martínez (born 17 June 1987) is a Mexican former professional footballer who played as a left-back.

Mares has been capped for the Mexico national team at the U-20 level, and played in the 2007 FIFA U-20 World Cup in Canada.

He played for most of his career in Santos Laguna, starting from 2006, and ending in 2015, when Club América purchased him after a year loan.

Other than Santos and America, he also had a stint with San Luis in 2010.

In February 2015, Mares scored his first goal for America in a Concacaf Champions League quarter final match against Saprissa, in which America won 2–0.