Richard Francis Hayes (1882 – 16 June 1958) was an Irish politician, historian and medical doctor.

He authored several major historical studies, including The Last Invasion of Ireland: When Connacht Rose (1st ed.

1937), which has been reappraised by Guy Beiner as a groundbreaking book for its use of oral traditions alongside more conventional archival sources.

For several years he was the closest friend of Frank O'Connor, who acknowledged the extraordinary help Hayes gave him in researching The Big Fellow, his biography of Michael Collins.

After some years, however, the friendship cooled, and the portrait of Hayes in O'Connor's memoir My Father's Son, is surprisingly unflattering, given their earlier closeness.