John Stephen "Thumper" DeMerit (January 8, 1936 in West Bend, Wisconsin) is a former professional baseball player. He was an outfielder over parts of 5 seasons (1957–1959, 1961–1962) with the Milwaukee Braves and New York Mets. DeMerit was a member of the 1957 World Series champion Braves. An alumnus of the University of Wisconsin–Madison, for his career he hit .174 with 3 home runs and 7 runs batted in in 93 games played.
