Theodore Otto Kleinhans was an American Major League Baseball pitcher. He was born in Deer Park, Wisconsin. Kleinhans played 4 seasons in Major League Baseball, with the Philadelphia Phillies and Cincinnati Reds in 1934, the New York Yankees in 1936, and the Reds again in 1937 and 1938. He had a career record of 4–9 in 56 games. He was the third oldest player in Major League Baseball in 1938.