John Ashley "Daff" Gammons (March 17, 1876 – March 24, 1963) was an American baseball and football player, college football and baseball coach, amateur golfer, and insurance agent. He played professional baseball for one season, 1901, for the Boston Beaneaters. Gammons served as the head football coach at Brown University in 1902, 1908, and 1909, and as its head baseball coach from 1901 to 1903.