Douglas Harper's Etymology Dictionary
fem. proper name, from Welsh bran "raven" + (g)wen "fair." Daughter of Llyr, she was one of the legendary heroines of Wales.
Wikipedia
Branwen, Daughter of Llŷr is a major character in the Second Branch of the Mabinogi, which is sometimes called the Mabinogi of Branwen after her. Branwen is a daughter of Llŷr and Penarddun. She is married to the King of Ireland, but the marriage does not bring peace.
Branwen is a 1995 British Welsh-language drama film directed by Ceri Sherlock. The film was selected as the British entry for the Best Foreign Language Film at the 68th Academy Awards, but was not accepted as a nominee.
Usage examples of "branwen".
Within, in silence, they walked past the mournful face of Branwen with her deep belly, and then of Conor her nigh-bald husband, and Midhir followed them through the fortress-house to the door of the chamber of Art mac Comail.
His stomach snarled, and he made Branwen relatively happy by stuffing his mouth with ham and his hand with pan-bread.
And thus sat they: the king of the Island of the Mighty and Manawyddan, the son of Llyr, on one side, and Matholch on the other side, and Branwen, the daughter of Llyr, beside him.