The big bad who's heading for the Seven Kingdoms is so evil, he makes Ramsay Bolton look like Santa Claus. The Night King takes no prisoners — unless you count his army of White Walkers and zillions of undead animals and humans, that is. The heroes and villains of Game of Thrones will have to band together if they want to defeat him — but first they have to figure out how to kill the Night King?
As Samwell Tarly discovered back in Season 3, stabbing a White Walker with dragonglass is a surefire way to finish them off. Jon Snow then added Valyrian steel to the list of stuff that can kill a White Walker in Season 5. Third, fire can also kill the wights — although it's powerless against Walkers. Cosmo's Laura Hanrahan also suggests that maybe dragon fire could kill the Night King, since it's got more magic in it than regular old flames.
In Season 7, Jon Snow, Tormund, Beric, Jorah, and the rest of the troop that headed north of the Wall discovered that killing one White Walker wipes out all the wights that Walker created. So it follows that killing the Night King could take out everyone in the Army of the Dead, wights and Walkers alike.
Nothing comes easily to the players in the Game of Thrones, though. And it's possible that Jon will become a little conflicted about taking on the leader of the Army of the Dead?
A popular fan theory suggests that Bran is actually the Night King, having gone back in time and assumed the identity of the first man that the Children Of The Forest transformed. The theory does seem possible, as we've already seen Bran warg into another person's body.
There is a faction of fans that aren't buying this theory, though. Bustle's Alexis Rhiannon points out that Bran can't be the Night King, because if the two were really the same person, why would the Night King have needed to brand Bran in order to attack him in the cave?
It would definitely make for an intriguing face-off if Jon Snow needed to go up against his half brother/cousin in the battle to end all battles. George R.R. Martin always promise a bittersweet ending to A Song of Ice and Fire, and killing a loved one in the process of saving the world would definitely fit the bill.
But is it possible to kill the Night King at all? Putting the Bran theory aside for the moment, showrunners David Benioff and D.B Weiss explained to Entertainment Weekly that death and the Night King are practically one in the same. "I don’t think of him as evil, I think of him as Death," Benioff said. "And that’s what he wants — for all of us. It’s why he was created and that’s what he’s after."
If the Night King truly can't be killed, that would explain why he escaped the War for the Dawn the last time around with nothing but a banishment North of the Wall. All men must die, but he's not really a man anymore, is he?