Donald John McMahon (January 4, 1930 – July 22, 1987) was a right-handed relief pitcher in Major League Baseball. Born in Brooklyn, New York, he was signed by the Boston Braves before the 1950 season. He played for the Milwaukee Braves (1957–62), Houston Colt .45s (1962–63), Cleveland Indians (1964–66), Boston Red Sox (1966–67), Chicago White Sox (1967–68), Detroit Tigers (1968–69), and San Francisco Giants (1969–74).