Muiredach Muillethan mac Fergusso (or Muiredach Mag Aí) (died 702) was a King of Connacht from the Uí Briúin branch of the Connachta. He was the grandson of  Rogallach mac Uatach (died 649), a previous king. He belonged to the Uí Briúin Ai sept. His sobriquet Muillethan means "broad-crowned".