Niamh is the lover or spouse of Oisín, son of Fionn mac Cumhail, in the Fianna Cycle of Irish mythology.
Niamh, illustrated by Beatrice Elvery in Heroes of the Dawn (1914)
Oisín, Osian, Ossian, or anglicized as Osheen was regarded in legend as the greatest poet of Ireland, a warrior of the Fianna in the Ossianic or Fenian Cycle of Irish mythology. He is the demigod son of Fionn mac Cumhaill and of Sadhbh, and is the narrator of much of the cycle and composition of the poems are attributed to him.
Ossian playing his harp, by François Pascal Simon Gérard, 1801
Oisín and Niamh on their way to Tír na nÓg, illustration by Albert Herter, 1899
The Dream of Ossian, Jean Auguste Dominique Ingres, 1813