For the Irish mythological character, see Oisín.

Oisín (pronounced in Irish as , with stress on first syllable) is an Irish male given name. It is sometimes anglicized as Osheen or spelt without the diacritic, as Oisin.

Oisín ( ; ), Osian or Ossian ( ) 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.