Branwen--"white raven" (bran > raven) (wen > gwen--f. of gwyn "white" "fair" or "blessed")
Bronwen: "white breast" (bron > breast--f. of bryn "hill")
Tragic figure of the tale Branwen uerch Llyr--"Branwen the daughter of Llyr." Sister to King Bendigedfran ap Llyr, she is given in marriage to the Irish King Matholwch, and bears him a son Gwern; however, her other brother Efniessin insults the Irish in numerous ways, causing Matholwch to take out his frustration on Branwen, beating her and forcing her to work as a scullery maid. When Bendigedfran (a.k.a. Bran) hears of this, he raises up an army to rescue his sister. A battle ensues, a magic cauldron which restores the dead is destroyed, and everyone dies, save five pregnant women in Ireland, and seven of Bendigedfran's warband--his brother Manawyddan, nephew Pryderi, the bard Taliesin, and four others (who don't really show up in other legends).
Branwen is said to have died of grief over the trouble, and is buried on the Isle of Anglesey* at a place called Tal y Bolon.
In later legends, she appears as Iseult's handmaid Brangwen, who aids the two lovers.
*boy, misspell one island, and everybody jumps on you!