The Night’s King is a legendary Lord Commander of the Night’s Watch, who lived during the Age of Heroes.According to legend, the Night’s King lived during the Age of Heroes, not long after the Wall was complete. He was a fearless warrior, who was named the thirteenth Lord Commander of the Night’s Watch. Later he fell in love with a woman “with skin as white as the moon and eyes like blue stars”, he chased her and loved her though “her skin was cold as ice”, and when he gave his seed to her he gave his soul as well. (Her description matches that of the Others.)
He brought her back to the Nightfort and after the unholy union, he declared himself king and her his queen, and ruled the Nightfort as his own castle for thirteen years. During the dark years of his reign, horrific atrocities were committed, of which tales are still told in the North. It was not until his own brother, the King in the North, and Joramun, the King-Beyond-the-Wall, joined forces that the Night’s King was brought down and the Night’s Watch freed. After his fall, when it was discovered that he had been sacrificing to the Others (possibly in similar way to Craster), all records of him were destroyed and his very name was forbidden. It is likely this led the lords of the North to forbid the Night’s Watch to construct walls at their keeps, ensuring the keeps would always be accessible from the south.