Bran
Bran the Blessed (Bendigeid Vran) is a king and demigod in British legend. After his sister Branwen marries the king of Ireland, their mistrustful relatives cause war between the nations; just when peace is at hand, his half-brother throws Branwen's son Gwern into a bonfire where he is consumed. In the battle that follows, Bran loses most of his followers (they have been killed before and were always revived using his magic iron cauldron, but the betrayer has destroyed the cauldron by casting his impure self into it). Sacrificing himself to redeem the kingdom, Bran persuades his men to cut off his head, which doesn't die; they travel with it for many years and bury it in London, this charm bringing peace to the island.
Bran is identified with the alder tree; Gwern's name means "alder," and the topmost branch of an alder is called "the singing head of Bran." EB