Harold Gust Carlson (May 17, 1892 – May 28, 1930) was a professional baseball pitcher in the Major Leagues from 1917 to 1930, for the Chicago Cubs, Philadelphia Phillies and Pittsburgh Pirates. Carlson used his curveball exclusively, owing to his lack of speed. He played seven years for the Pirates, going 42-55, went 42-48 in four years with the Phillies, and had a mark of 30-17 with the Cubs in four years. He had his most wins in 1926, with 17 (along with 12 losses). He had a career best 2.23 ERA in 1919.