If one were to hear a Game of Thrones fan discussing the “Night’s King,” one might assume that they were simply misnaming the Night King—antagonist supreme of the series. However, if said fan were also a reader of the A Song of Ice and Fire novels that preceded the series, there’s a good chance they’re actually discussing the 13th Lord Commander of the Night’s Watch—who is known in Westerosi history books as the Night’s King.
There are as many differences as similarities between Game of Thrones’s Night King and the Night’s King of Westeros’s ancient past. Though the characters are distinct, there are enough parallels between their stories that a close reading of the tale of the Night’s King could yield clues about his show-only counterpart—and thus hint at the series’ ultimate endgame. After all, history has a nasty habit of being cyclical when it comes to the World of Ice and Fire.
Diehard Game of Thrones fans who try to pick up the A Song of Ice and Fire books after the series concludes will no doubt be confused at the lack of a Night King. In the novels, the White Walkers are known as the “Others”—and they don’t have any singular leader. There is, however, a figure in the ancient history of Westeros known as the Night’s King—but he’s an entirely separate entity than the being threatening the show's Winterfell, and has long since faded from existence.
George RR Martin himself has confirmed the lack of a Night King in the books, stating on his LiveJournal that “As for the Night's King (the form I prefer), in the books he is a legendary figure, akin to Lann the Clever and Brandon the Builder, and no more likely to have survived to the present day than they have.”
The Night’s King appears in both the books and the television adaptation as a figure from the distant past of Westeros. Specifically, the Night’s King and his corpse bride come from a time period known as the “Age of Heroes”—a semi-mythical era that occurred thousands of years before the events of Game of Thrones.
The Age of Heroes is interrupted by the Long Night, the last time the Others attempted to invade Westeros—and almost succeeded. The Long Night is followed by the construction of The Wall and the founding of the Night’s Watch, and the story of the Night’s King follows several generations thereafter, but his tale is still full of vital information about the White Walkers.
The true name of the figure known as the Night’s King is lost to history, but his status as the 13th Lord Commander of the Night’s Watch is not. The Night’s King is one of the earliest individuals to fill the role that Jeor Mormont and Jon Snow would one day hold. And he's the first to abandon his duty.
The election of the Night’s King as Lord Commander happens within a few hundred years of the Long Night, a time period in which the threat of another invasion by the White Walkers must have seemed imminent. Those circumstances are what make the betrayal of the Night’s King all the more unforgivable—and give his storyline yet another parallel to that of Jon Snow.
Like many other characters in A Song of Ice and Fire, the Night’s King makes a questionable decision in the name of love, but his situation is a little more supernatural than the average Westerosi romantic drama. While serving as the Lord Commander of the Night’s Watch, he encounters a woman “with skin as white as the moon and eyes like blue stars.”
The woman, described occasionally as a corpse bride and other times as the Night’s Queen, seduces the Night’s King away from his duty—taking both his seed and his soul if the legends are to be believed. Fans of the series have driven themselves wild trying to guess as to the modern-day equivalent to the Night’s Queen—with candidates ranging from Daenerys Targaryen to Cersei Lannister.