There have been many theories swirling around who the leader of the White Walkers really is, but the most prevalent theory at this time, according to Ranker, is that the Night King is a Stark ancestor.
The outlet cites a strong connection that the Night King has to the family, as well as clues in the show's novel series.
There have also been theories that the Night King may be a Targaryen.
The actor who plays the Night King is named Vladimir Furdik, and earlier this year he opened up about the role and stated that his character is intent on bringing down someone specific, though he did not divulge who.
"People will see he has a target he wants to kill, and you will find out who that is. There's also that moment [in "Hardhome"] when Jon Snow was on the boat and the Night King looked at him and raised his arms — there's a similar and even stronger moment between Jon and the Night King this time," Furdik stated.
Regarding the Night King's motivation, Furdik explained, "Somebody made him the Night King. Nobody knows who he was before — a soldier or part of [nobility]. He never wanted to be the Night King. I think he wants revenge. Everybody in this story has two sides — a bad side and a good side. The Night King only has one side, a bad side."
Furdik began playing the Night King in Season 6 of Game of Thrones, taking over the role from actor Richard Brake. When asked how he came to earn the role, Furdik replied, "I don't really know why they cast me."
"When we did season 5, I was the White Walker who fought Jon Snow [in "Hardhome"] — the first time Jon Snow killed a White Walker, that was me. After that, [showrunners David Benioff and D.B. Weiss] asked if I'd play the Night King for seasons 6 through 8. I never asked why. Maybe they were happy with what I did in season 5," he added.
Lastly, Furdik shared that he rarely gets recognized, but that it does happen sometimes, and reactions are often mixed.
"Many people ask me: 'Can you please kill Jon Snow?' It's very interesting. Sometimes I watch YouTube reactions after the season airs. Fifty percent of people love the Night King and 50 percent of people hate him. And since I replaced Richard Blake, some people like how I play him and some don't," Furdik said.
Game of Thrones Season 8 airs Sundays at 9 p.m. ET on HBO.