John J. "Jack" Clements (July 24, 1864 – May 23, 1941) was an American professional baseball player. He played as a catcher in Major League Baseball for 17 seasons. Despite being left-handed, Clements caught 1,076 games, almost four times as many as any other left-handed player in major league history and was the last left-hander to catch on a regular basis. He is credited with being the first catcher to wear a chest protector.