John Blyth Hayes CMG (21 April 1868 – 12 July 1956) was an Australian politician who served as a Senator for Tasmania from 1923 to 1947. He was President of the Senate from 1938 to 1941. Before entering federal politics, he had been a member of the Parliament of Tasmania from 1913 to 1923 and served as Premier of Tasmania for almost exactly one year, from 1922 to 1923.