With only five episodes left in Game of Thrones, viewers are going wild theorizing about how it will all end. And as the looming conflict between the armies of the living and the dead approaches, one question has risen to the top of the queue: is the Night King on Game Of Thrones a Targaryen? While fans have been speculating for years about the identity of the White Walker head honcho, this is a relatively new theory that cropped up in the wake of the Season 8 premiere, "Winterfell." Fortunately, unlike a lot of the show's long-standing mysteries, this one should be relatively easy to answer by taking a look at the evidence.
First of all, let's break down why some viewers are convinced there's a connection between the Night King and Daenerys' family. The theory's roots go back to the Season 7 finale, when the villain showed up at Eastwatch on the back of undead Viserion and blasted down the Wall. What does this have to do with the Night King's lineage? Operating under the belief that only a Targaryen can ride a dragon, many fans assumed that his mastery of Viserion meant the Night King must have some of the blood of Old Valyria in him.
This suspicion was confirmed in the eyes of some fans with the first episode of the final season, when the Night King left a mysterious message on the wall of the Last Hearth, the ancestral castle of House Umber. As the wheel of dismembered limbs caught on fire, the symbol came to resemble the sigil of House Targaryen, according to some, with the spiral arms echoing the curved necks, wings, and tail of the three-headed dragon. (The same spiral symbol was also seen in the cave paintings under Dragonstone, which is of course the seat of Targaryen power in Westeros.)
Finally, there's the prophecy in the books that "the dragon has three heads." Although this moment never made it onto the show, Daenerys receives this prophecy while wandering through the House of the Undying in A Clash Of Kings, spoken to her by a specter of her slain brother, Rhaegar. If the Night King is one of those three prophesied heads of the dragon — and that prophecy was spoken by Rhaegar — could the Night King be Rhaegar Targaryen himself? Some fans think so, positing that the crown prince was turned by the Children of the Forest after being killed by Robert Baratheon at the Battle of the Trident, and that he's invading Westeros to reclaim the throne that was stolen from him.
Now let's examine the evidence against this theory. First of all, the show has never directly confirmed whether or not Targaryens are the only people who can ride dragons. That's something book-readers have assumed for years — but the fact that Daenerys encouraged Jon to mount Rhaegal and seemed unphased when her lover succeeded certainly implies that the Mother of Dragons herself is unaware of this fact, even if it is true. (And if it is true, it's possible that Viserion is now more of a wight and less of a dragon by nature, explaining how the Night King could ride the undead beast even without Targaryen blood.)
As for the spiral symbol, the Season 8 premiere was far from the first time the Night King has left such a message behind. A form of it was glimpsed in the opening sequence of the very first episode, although it looked a bit different than the many-armed spiral the showrunners would eventually settle on as the White Walkers' calling card. It was seen again in the aftermath of their attack on the Fist of the First Men and in the stones around the weirwood tree where the Children created the Night King. This symbol has been linked with the White Walkers since their inception, and seems to have more to do with referencing their origins than announcing their identity as Targaryens.
The timing doesn't work out, either. The Children created the first White Walker thousands of years ago, when they were at war with the First Men. That was centuries before even the Andals came to Westeros and spread the religion of the Seven, after which several more centuries passed before the first Targaryens arrived in Westeros and forged the continent into the Seven Kingdoms. (The Night King certainly can't be Rhaegar, who only died a couple decades before the start of Game Of Thrones, not thousands of years ago.)
Besides, we've already seen the Night King in his human form before he was turned: does this look like a Targaryen to you?
It's certainly not Rhaegar, who we saw in Bran's vision in the Season 7 finale looking very much like his younger brother Viserys. But it's also certainly not a person of any Targaryen lineage, bearing none of the trademark characteristics of the family — most notably, their long silver hair.
While I suppose it's technically possible that there have been many Night Kings over the years — just as there have been many kings of Westeros — and that the current White Walker holding that title is some Targaryen or other, I'm pretty confident in calling this theory the product of an over-imaginative fanbase whose speculations are going into overdrive now that their favorite show is finally back. It seems much more likely that the long-standing theory that the Night King is a Stark will hold true in the end.