Gary Leah Thomasson (born July 29, 1951) is an American former professional baseball player. He played as an outfielder and first baseman in Major League Baseball (MLB) between 1972 to 1980, most prominently as a member of the San Francisco Giants with whom he played for seven seasons. He also played for the Los Angeles Dodgers, New York Yankees, Seattle Mariners, Montreal Expos, and the Cincinnati Reds. After his Major League Baseball career, he played for the Yomiuri Giants of Japanese Nippon Pro Baseball from 1981 to 1982. Thomasson was a member of the Yankees' 1978 World Series winning team over the Dodgers.