In Irish traditional history Eógan (or Eoghan Mór—a name also used by his grandfather, Mug Nuadat), eldest son of Ailill Ollamh, was a 2nd or 3rd century AD king of Munster. He is credited with founding or at least giving his name to the Eóganachta, a dynasty which ruled as kings of Munster and later princes of Desmond until the late 16th century. The son of Éogan Mór was Fiachu Muillethan.
His mother was Sadb ingen Chuinn, daughter of Conn of the Hundred Battles.