Nienna, according to Tolkien’s Middle-earth mythology is another member of the Valar, the Ainur that are in charge of the world and bound to it until it ends. She is the mourner, she is well-acquainted with grief. She is the sister of Lórien and Mandos, one of the feanturi. She wept for the Two Trees when they were destroyed and by watering the mound of earth with her tears, helped Yavanna raise them up again to each bear one fruit, which were then placed in hallowed containers and became the sun and moon.
She remains with her brother in the Halls of Mandos, comforting those who have died and giving quiet strength to those that mourn.