Oisín (Irish pronunciation: [ɔ'ʃiːnʲ] ush-EEN; anglicized often as /oʊˈʃiːn/ oh-SHEEN), Osian, Ossian (/ˈɔːʃən/ AW-shən), or Osheen was regarded in legend as the greatest poet of Ireland, and is a warrior of the fianna in the Ossianic or Fenian Cycle of Irish mythology. He is the son of Fionn mac Cumhaill and of Sadhbh (daughter of Bodb Dearg), and is the narrator of much of the cycle.
His name literally means "young deer" or fawn, and the story is told that his mother, Sadbh, was turned into a deer by a druid, Fear Doirche (or Fer Doirich). When Fionn was hunting he caught her but did not kill her, and she returned to human form. Fionn gave up hunting and fighting to settle down with Sadbh, and she was soon pregnant, but Fer Doirich turned her back into a deer and she returned to the wild. Seven years later Fionn found his child, naked, on Benbulbin. Other stories have Oisín meet Fionn for the first time as an adult and contend over a roasting pig before they recognise each other.