Gregory Inman Mathews (born May 17, 1962) is an American former professional baseball pitcher. He played all or parts of five seasons in Major League Baseball between 1986 and 1992 for the St. Louis Cardinals and the Philadelphia Phillies.

Mathews is an alumnus of Savanna High School in Anaheim, California, and of California State University, Fullerton. He played summer collegiate baseball for the Hazlet Elks of the Saskatchewan Major Baseball League in 1986 prior to playing in the majors. During his rookie year Greg put up a 3.65 ERA in 145.1 innings. His 11 wins in 1986 were the most by a Cardinal rookie since Brooks Lawrence had 15 in 1954; Luis Arroyo also had 11 wins as a rookie in 1955.^[1] His best year is most likely 1987, when he posted a 3.73 ERA, won 11 games and struck out 108 batters.

He lives in Buena Park, California.