James Phillip Austin was a Welsh professional baseball player and coach. He played in Major League Baseball as a third baseman for the New York Highlanders and St. Louis Browns from 1909 through 1923, 1925 through 1926, and 1929. He also managed the Browns in 1913, 1918, and 1923.

A third baseman, abbreviated 3B, is the player in baseball or softball whose responsibility is to defend the area nearest to third base — the third of four bases a baserunner must touch in succession to score a run. In the scoring system used to record defensive plays, the third baseman is assigned the number 5.