Ethlinn

In Goidelic mythology, Ethlinn was the daughter of Balor, the god of death.

According to a prophecy, Balor was to be killed by his grandson. He locked Ethlinn in a tower made of crystal to keep her from becoming pregnant. However, Cian, one of the Tuatha de Danaan, with the help of the druidess Birog, managed to enter the tower. She gave birth to a son, Lugh, by him, but Balor threw him into the ocean. Birog saved him and gave him to Manannan mac Lir, who became his foster father.