The Night King is not the show's main villain
Ever since the death of Ramsay Bolton at the hands of his hungry, hungry hounds, there's been discussion about the the villain vacuum on Game of Thrones. With Ramsay, Joffrey, and the High Sparrow all gone, who will torment us every Sunday night? One idea is that the Night King, who typically drops by once a season to commit some horrible act of violence, will step up to fill the void. But according to Benioff and Weiss, the frosty undead leader is not the villain you're looking for.
"We don't think of the Night King as a villain as much as Death," the pair write in the interview. "He is not someone who's like Joffrey or Ramsay. He's not really human anymore. Evil comes when you have a choice between that and good, and you choose the wrong way. The Night King doesn't have a choice; he was created in that way, and that's what he is. In some ways, he's just Death, coming for everyone in the story, and for all of us."
What does that mean going forward? It's hard to say, especially because "he's just Death" is a metaphoric way writers often talk about textbook "villains" like the Joker or Anton Chigurh. In the interview the pair say it's appropriate that the Night King doesn't speak, so don't expect a series of scenery-chewing monologues to come from his blue, icy mouth anytime soon. He probably won't join forces with Daenerys and ride a dragon around.