4. THE NIGHT KING
Not much is known about the White Walkers. We know that the Night King has been creating White Walkers with the baby boys that Craster offered up as tribute, a process we saw in season four episode “Oathkeeper” (written by Bryan Cogman). However, in the season six episode “The Door” (written by Benioff and Weiss), it was revealed that Leaf created the Night King by forcefully burying a shard of dragonglass into one of the First Men.
We know that he can create White Walkers, raise the dead and reach people using the Sight as we saw in “The Door” when he touched Bran in a vision, leaving a physical mark on his arm and using it to gain access to the three-eyed raven’s sanctum. We can probably assume the war against the White Walkers definitely won’t be won using the Sight. How will it be won, then? Will the Night King die in a dragon fire or could we see him somehow return to mortal flesh?