Gregory Eugene Gross is an American former professional baseball outfielder and pinch hitter who played 17 seasons in Major League Baseball (MLB), primarily for the Philadelphia Phillies. He was previously the Phillies' hitting coach and a former manager for the Reno Aces, the Arizona Diamondbacks' Triple-A affiliate.

In baseball, a pinch hitter (PH) is a substitute batter. Batters can be substituted at any time while the ball is dead ; the manager may use any player who has not yet entered the game as a substitute. Unlike basketball, American football or ice hockey, and in a similar way to association football, baseball does not have a free substitution rule and thus the replaced player is not allowed back into that game. The pinch hitter assumes the spot in the batting order of the player whom he replaces. Pinch hitters are commonly used to replace a weak hitter or to gain a platoon advantage.