Robert T. Mathews (November 21, 1851 – April 17, 1898) was an American right-handed professional baseball pitcher who played in the National Association of Professional Base Ball Players, the National League of Major League Baseball and the American Association for twenty years beginning in the late 1860s. He is credited as being one of the inventors of the spitball pitch, which was rediscovered or reintroduced to the major leagues after he died. He is also credited with the first legal pitch which broke away from the batter. He is listed at 5 feet 5 inches tall and 140 pounds, which is small for a pro athlete even in his time, when the average height of an American male in the mid-19th century was 5 foot 7.