Charles Herbert Klein (October 7, 1904 – March 28, 1958), nicknamed "the Hoosier Hammer" because of his Indiana roots, was an American professional baseball outfielder. Klein played in Major League Baseball (MLB) for the Philadelphia Phillies (1928–1933, 1936–1939, 1940–1944), Chicago Cubs (1934–1936), and Pittsburgh Pirates (1939).
Klein led the National League (NL) in home runs four times, and won the NL Most Valuable Player Award in 1932. In 1933 he became one of six (at the time) NL players to win a batting Triple Crown. In 1930 he set the NL record for extra-base hits with 107. On July 10, 1936, he hit four home runs in a game, becoming the fourth player to do so. He was the first player to be selected to the All-Star Game as a member of two different teams (Phillies and Cubs). Klein was elected to the Baseball Hall of Fame in 1980.