1970’s The Tombs of Atuan is the second volume in Ursula K. Le Guin’s Earthsea Cycle.
The influence of the Nameless Ones has dwindled over the long ages, but they still have power in the Tombs of Atuan. There they still are worshipped. There they are served by their immortal Priestess.
The little girl once named Tenar is the latest incarnation of the Priestess. The bodies of the One Priestess of the Tombs of Atuan die, but the Priestess lives on, reborn in a newborn body at the time of the Priestess’ death. Stripped of her birth family and her name, the girl who was Tenar becomes Arha, “the eaten one,” paramount human servant of the ancient and fearsome Nameless Ones.