Branwen is also the name of a character in some versions of Tristan and Iseult.

Branwen, Daughter of Llyr 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 Llyr and Penarddun. She is married to the King of Ireland, but the marriage does not bring peace.