Foster Leroy Witherup (July 26, 1886 – December 13, 1941) was a professional baseball pitcher. He played all or part of three seasons in Major League Baseball between 1906 and 1909 for the Boston Beaneaters (1906) and Washington Senators (1908–09). Listed at 6 ft 0 in (1.83 m), 185 lb., Witherup batted and threw right-handed. He was born in North Washington, Pennsylvania. Witherup died in New Bethlehem, Pennsylvania, at the age of 55.