If you've been trying to do the mental gymnastics to figure out how this theory could possible make sense, then you'll be relieved to hear that Bran Stark isn't the Night King on Game Of Thrones. Or, at least, someone involved with the show doesn't see how it's possible: Isaac Hempstead Wright, who has portrayed Brandon Stark/The Three-Eyed Raven since Season 1, told New York Magazine that Bran Stark isn't the Night King. Sure, Game of Thrones actors can lie, lie, lie (ahem, Kit Harington), but Wright's thoughts about Bran are compelling in a different way.
"I think it’s less that they’re the same person and more that they’re two of the ancient beings of Westeros," the actor said. "....Perhaps we can think of it as these are two characters with a huge amount of power, but one is a Frankenstein’s monster who is driven by nothing but hatred and violence. Then there’s Bran, who uses his powers for good." The paragon of humanity and its greatest destroyer? Now, there's a tale as old as time, one that makes more sense than Bran being the one trying to massacre all of Westeros.
With just one abbreviated season left before the series ends, the Bran Stark is the Night King theory gripped Game of Thrones fans around the world. It's spooky and it's weird and it helps explain a lot of long, ominous sequences wherein the Night King apparently connects with Bran. It's also, of course, absurd. A lot of psychic warping of the time-space continuum would have to happen on screen to make that plausible, and there are only so many episodes of the series left.
Of course, this could all be an elaborate ploy to dissuade fans from the Night King theory. After all, what would a grand reveal like that be if HBO admits that the conspiracy theorists got it right? Furthermore, while Bran Stark isn't the Night King right now, he might become him in a future episode. The use of semantics and flat-out lies has been a staple for the cast to keep fans guessing until the episodes aired; remember when Maisie Williams admitted she loves lying to fans about the show?
It's also worth noting that Wright mentions that he hasn't yet seen even one script for Season 8. The Lord of Light knows that could mean anything. But, for now, Bran Stark is telling us that he's absolutely not the Night King, so we have to believe him. Though only for now.