Kenneth Leo Retzer (April 30, 1934 – May 17, 2020) was an American professional baseball player. He was a catcher in Major League Baseball for the Washington Senators from 1961 to 1964, appearing in 237 games played. Retzer batted left-handed, threw right-handed and was listed as 6 feet (1.83 m) tall and 185 pounds (84 kg). He finished his career with a lifetime batting mark of .264, 182 hits, 14 homers, 72 runs batted in and 65 runs scored. He had a lifetime fielding percentage of .983 and threw out 48 of 126 baserunners making stolen base attempts, a rate of 38.1 percent.