Max John Flack (February 5, 1890 – July 31, 1975) was a Major League Baseball outfielder. He played twelve seasons in the majors from 1914 to 1925 for the Chicago Chi-Feds/Whales (1914–15) of the Federal League, then the Chicago Cubs (1916–22) and the St. Louis Cardinals (1922–25) of the National League.