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).McMahon was used almost exclusively in relief during his 18-year MLB career. He appeared in 874 games, just two as a starter, and was one of the major leagues' busiest and most dependable relievers during his era. He never once spent time on the disabled list, and in the fifteen full seasons that he played (1958–72), he averaged about 54 games and 81 innings pitched per year.