Wikipedia
In Irish mythology, Noíse or Noisiu (modern spelling: Naoise; Irish pronunciation: ) was the nephew of King Conchobar mac Nessa of Ulster, and a son of Usnech (or Uisliu), in the Ulster Cycle.
When Deirdre (Derdriu) was born, Cathbad the druid prophesied that she would be beautiful, "a woman with twisted yellow tresses, green-irised eyes of great beauty and cheeks flushed like the foxglove," but that kings and lords would go to war over her. Conchobar decided to have her brought up in seclusion, and that when she was old enough, he would marry her. However, one day when she saw her foster father skinning a calf in the snow she told her nurse that she desired a man who had hair like the raven drinking the blood of the calf, cheeks like the blood, and skin like the snow. She said she would be ill until she met the man with this description. Naoise fit her description of the man she would love and when she met him alone in a field she fell in love with him. He was a handsome and talented young warrior, hunter and singer. Naoise knew that Deirdre belonged to Conchobar and tried to reject her, but eventually gave in and they eloped.
Naoise's two brothers, along with fifty warriors and fifty women helped the couple escape Conchobar. They continued to travel throughout Ireland as Conchobar tried numerous times to destroy them and get his betrothed back.
They fled to Scotland, (or Alba in the Old Irish translations), where the King allowed the group to join their people. Naoise kept Deirdre hidden from the people so there could not be killing on her account. One day a steward saw the girl and told the king that if he had Naoise killed, the beautiful girl could be his. In order to avoid being killed, Naoise and his brothers fled Alba. Not wanting their own people to be killed by enemies the people of Ulster begged Conchobar to forgive the couple and allow them to return safely. Conchobar agreed and sent Fergus mac Róich to them with a message of safe conduct home. On the way back to Emain Macha, however, the group was waylaid by Conchobar, who had Naoise and his brothers murdered by Eogan mac Durthacht, king of Fernmag, so he could forcibly marry Deirdre. Fergus, outraged by this betrayal of his word, went into exile in Connacht. Deirdre committed suicide by leaning out of her chariot and dashing her head against a rock after Conchobar threatened to give her to Eogan mac Duthacht. In later versions of the story, she died of grief, or stabbed herself.