Constantine Gregory "Gus" Niarhos (December 6, 1920 – December 29, 2004) was an American professional baseball player. He played in Major League Baseball as a catcher for the New York Yankees (1946, 1948–50), Chicago White Sox (1950–51), Boston Red Sox (1952–53) and Philadelphia Phillies (1954–55). Niarhos batted and threw right-handed, stood 6 feet (1.8 m) tall and weighed 160 pounds (73 kg).