He had only one child, the "flower of woman" Plur nam Ban, but left her behind in the Land of Promise to return to his own world.  This followed his battle with the giant Fomori and his romance with Manannan Mac Lir's daughter, Niamh.  His own youth 
He had only one child, the "flower of woman" Plur nam Ban, but left her behind in the Land of Promise to return to his own world.  This followed his battle with the giant Fomori and his romance with Manannan Mac Lir's daughter, Niamh.  His own youth was spent with his mother, the goddess Sadb, who was enchanted as a beautiful deer until she met this child's father.  Thus, he was given a name meaning "Little Fawn" when he was reunited with his father, the leader of the Fenians.  For 10 points - name this greatest of the Irish poets and son of Finn Mac Cool.
He had only one child, the "flower of woman" Plur nam Ban, but left her behind in the Land of Promise to return to his own world.  
Ossian (osh-en) or Oisin