Gregory Louis Bonin (born June 15, 1955) is an American former professional baseball umpire. Bonin worked in the National League from 1984 to 1999, and in both major leagues in 2000 and 2001, wearing uniform number 34 for his entire career. He umpired in 1,746 major league games in his 18-year career. He umpired in one All-Star Game (1991), one National League Championship Series (1998), and two Division Series, 1996 and 1997.