Niamh

Oisin was a member of the Fianna and, though he fell in love with Niamh and returned with her to Tir na N-Og, he became homesick after what he thought was three years. Niamh let him borrow Embarr, who could run above ground, and made him promise not to touch Irish soil.

The three years he spent in Tir na n-Og turned out to be 300 Irish years and Oisin fell off Embarr, instantly becoming an old man. Meanwhile, Niamh had given birth to his daughter, Plor na mBan. Niamh returned to Ireland to search for him, but he had died.