Dark Druid (Fer Doirich)

The Dark Druid or Fer Doirich was a powerful druid who loved Sadb, daughter of Derg Díanscothach of Síd Ochta Cleitigh or of Bodb Derg son of Dagda.

Because Sadb refused to love him, the Dark Druid transformed her into a fawn. The Fenian hero Finn Mac Cumhaill found her and broke the magic of the druid that was upon Sadb. Finn fell in love with her and married her. Sadb fell pregnant.

But the Dark Druid took her back, abducting her when Finn was absent in a war. Again, Sadb refused to love him, so he turned her back into a fawn. She gave birth to a baby boy, whom Finn named Oisín. Oisín was the last person to see his mother as she followed the Dark Druid, leaving him behind.