O.K., what follows is a quick refresher course on who the Night’s King on Game of Thrones is, followed by some spoilery speculation on why he matters. If you already know all there is to know about the Night's King, feel free to jump to the spoiler section below to find out why he matters.

So the Night’s King is, of course, that stone-cold badass we saw get the best of Jon Snow and the Wildlings at Hardhome tonight. There seems to be no fighting this caliber of White Walker unless (as per legend in the George R.R. Martin books) you have a sword made of Valyrian steel (a.k.a. dragon steel). Jon has one, Longclaw, which was given to him by Lord Commander Mormont. (The importance of Valyrian steel was reinforced by the “previously on,” but in the show version Jon Snow could be Neo for all we know.) The Night’s King has his eye on Jon now after this.

You can tell which of those elegantly dressed White Walkers was the Night’s King by the “crown” of pointy, frosty horns on his head. He showed up last season to touch a baby and turn its eyes frosty blue. He resurrected a whole Hardhome full of slain Wildlings in this week’s episode. The name of this character, the Night’s King, was accidentally leaked by HBO last season. The character hasn’t even shown up in the book yet but is described on the Game of Thrones wiki as follows:

According to legend, the Night’s King lived during the Age of Heroes, not long after the Wall was complete. He was a fearless warrior, who was named the thirteenth Lord Commander of the Night’s Watch. Later he fell in love with a woman “with skin as white as the moon and eyes like blue stars,” he chased her and loved her though “her skin was cold as ice,” and when he gave his seed to her he gave his soul as well.

That’s right, the Night’s King is a former Lord Commander. Just like Jon Snow. The wiki goes on to say:

He brought her back to the Nightfort and after the unholy union, he declared himself king and her his queen, and ruled the Nightfort as his own castle for thirteen years. During the dark years of his reign, horrific atrocities were committed, of which tales are still told in the North. It was not until his own brother, the King in the North, and Joramun, the King-Beyond-the-Wall, joined forces that the Night’s King was brought down and the Night’s Watch freed. After his fall, when it was discovered that he had been sacrificing to the Others (possibly in similar way to Craster), all records of him were destroyed and his very name was forbidden. It is likely this led the lords of the North to forbid the Night’s Watch to construct walls at their keeps, ensuring the keeps would always be accessible from the south.

There are also rumors that, during his human life, the Night’s King was a Stark named Bran. Hmmmm. So what do we know? The Night’s King is a former Lord Commander who, as was displayed in this episode, is very skilled at bringing people back from the dead. Why does that matter? Let’s discuss below the spoiler warning.

Those who have read the books (or indulged in spoilers) will expect that when Jon Snow returns to the Wall from Hardhome he won’t be very popular. In the books, Snow is stabbed multiple times by his fellow watchmen as part of a mutinous plot. We can expect that in the show this mutiny will be lead by that perma-grouch Alliser Thorne. Olly’s role in the mutiny is still somewhat up in the air, but he’s not sounding very loyal of late, is he? But as far as the last completed George R.R. Martin book, A Dance with Dragons, is concerned, Jon Snow is presumed dead; stabbed to death by his comrades at arms.

Despite the high body count among the heroes of Game of Thrones, most readers have never believed that cliffhanger or Jon Snow’s death would stick. There are a few options when it comes to bringing a human back from the dead on Game of Thrones. We can assume Melisandre is capable of something like that. She might need to burn a lot of royal blood to pull it off, but I wouldn’t put it past her. Carice Van Houten said she has another big scene with Kit Harrington in Season 5, so the Red Woman is a possibility. We also know, from Season 3, that the red priest Thoros of Myr can bring people back from the dead. He’s done it several times with Beric Dondarrian. One theory as to why the show hasn’t given us Thoros of Myr resurrecting Lady Stoneheart (a.k.a. Zombie Catelyn Stark) is that creators Dan Weiss and David Benioff didn’t want to ruin the surprise behind a Myrish resurrection of Jon Snow.

But what if it’s neither of those options? What if it’s the Night’s King who brings Jon Snow back from the dead? I’m not talking about bringing him back as a mindless wight destined to go all skeletal. What if the Night’s King sees something special in Jon Snow? Maybe he sees an heir to his icy throne? What if this season ends with Jon Snow opening an icy blue eye and going to the dark side? (It might make a nice visual parallel to what I presume will be an eye-heavy final shot for Maisie Williams this season.) He might be an evil Jon Snow for a bit before being redeemed by the magic of his brother Bran. He might stay evil and lead the forces of the dead against Daenerys Targaryen. (Ice vs. Fire, anyone?) Or he might retain his character and just have an alluring new eye color next year. But one thing is for certain, the Night’s King has a major role to play in all this and that “ARISE!!!” scene can’t be a coincidence.