Who is the Night King?

Where does the Night King come from in the show?

The series answers it in its sixth season, through one of Bran Stark's visions. Long ago, the Children of the Forest made the White Walkers to protect themselves from mankind, beginning with a captured man of the First Men whom they changed with a blade of dragonglass. The Night King is that first creation, and the one who leads the rest of them across all eight seasons.

The origin turns the threat into a story about consequences. The monsters at the edge of the world were not an outside evil but a defence that escaped its makers, and the same material that made the Night King, dragonglass, is one of the few things that can destroy his kind. The show uses that symmetry to tie its ending to its oldest history: the war against the dead is a war one ancient people started against another.

How is he different from anything in the novels?

The Night King, as the series presents him, has not appeared in the published novels. The books have the Others, the cold creatures behind the show's White Walkers, but no single named leader with a face and a plan. In print the Others are glimpsed far more than they are explained, which makes them feel more alien than any one villain could.

What the books do have is a legend with a similar name. The Night's King, in the stories told in the North, held the Watch's command as its thirteenth leader, back in the Age of Heroes, and the tales cannot even agree on who he was; one storyteller suggests he was a Stark. He is a figure of folklore, not a character who walks into the story, and the show borrowed the title while building something new around it.

Why does the show give the dead a single leader?

Because television needs a face. A threat that is plural and silent works on the page, where a reader can be unsettled by absence, but an eight-season drama needs someone the audience can watch arrive, someone who can look at a hero and be looked back at. The Night King gives the army of the dead an intention, which turns a natural disaster into an opponent.

The choice also simplifies the ending. If one figure leads the dead, then destroying that figure can end the war in a single moment, which is exactly how the series resolves it. Critics who wanted the threat to remain larger than any one blow see that as the cost of the change; others see it as the clean dramatic payoff the show had been promising since he first appeared in its fourth season.

Why is Arya the one who destroys him?

The story gives the blow to a character trained in Braavos by the Faceless Men rather than to any of the people prophecy had pointed at. Arya has spent years learning to reach a target unseen, and the series frames her success as the payoff of that training rather than of destiny. That is also why the moment unsettles viewers who expected Jon Snow, the long-presumed hero, to finish the war.

It changes how the show's prophecies read in hindsight. Melisandre spent seasons searching for the promised hero, and the decisive act falls to someone outside every candidate she named, using a Valyrian steel dagger rather than a burning sword. Whether that is the show deliberately undercutting prophecy or simply moving past it, the result is that the Night King's story ends as a story about skill rather than about fate.