Night's King

No one agrees on who he was. Some say a Bolton, others a Magnar out of Skagos, or an Umber, a Flint, a Norrey, even a Woodfoot. Every northern house has its own version, and none of them wins out over the rest.

Old Nan tells a different one: a Stark of Winterfell who became the thirteenth Lord Commander of the Night's Watch, perhaps named Brandon. Bran hears it as a boy, long before he himself reaches the Nightfort where it all supposedly happened.

The story paints him as a warrior afraid of nothing, until he crossed paths with a woman with skin white as the moon and eyes like two blue stars. The cold of her skin should have warned him: it is the same description given for the Others.

He brought her to the Nightfort and set her beside him as queen. They ruled together for thirteen years, and in that time the sworn brothers stopped being a watch and became the Queen's own army, bound to her will by spells no one fully explains.

He was brought down by an unlikely alliance: Brandon the Breaker, King in the North, whom Old Nan also names as his own brother, and Joramun, King-Beyond-the-Wall, leading the Free Folk. Together they defeated him and ended his rule over the Nightfort.

After his defeat it came out that he had been sacrificing people to the Others. The answer was to erase him entirely: the records concerning him were destroyed, and even his true name was eventually lost.

The maesters, for their part, doubt the undead wife altogether and point to something more earthly: she may simply have been the daughter of some Barrow King.