John Williams Joseph "Bunny" Roser (November 15, 1901 – May 6, 1979) nicknamed "Jack", was a professional baseball player. He was an outfielder for one season (1923) with the Boston Braves. For his career, he compiled a .239 batting average in 113 at-bats, with 16 runs batted in.
He was born in St. Louis, Missouri and died in Rocky Hill, Connecticut at the age of 77.