Martin Gordon DeMerritt (born March 4, 1953) is an American professional baseball coach and a former minor league pitcher. In 2018, he spent his sixth straight season as the pitching coach of the Rookie-level GCL Rays of the Gulf Coast League. He served two different terms in Major League Baseball as a coach for the San Francisco Giants (1989) and Chicago Cubs (1999). In 2001, the Tampa Bay Devil Rays hired DeMerritt as a pitching coach at the Class A level, and he has remained in the Rays' system since, working with pitchers at the lower levels of the minors for 18 seasons.