George Jasper Caster (August 4, 1907 – December 18, 1955), nicknamed "Ug", was a right-handed professional baseball pitcher for 21 years from 1929 to 1948 and again in 1953. He played 12 years in Major League Baseball with the Philadelphia Athletics (1934–1935, 1937–1940), St. Louis Browns (1941–1945), and Detroit Tigers (1945–1946). Caster became known as an early knuckleball pitcher. He played for American League pennant winning teams in both 1944 and 1945.