House Stark (or, Westeros's most powerful house)
House Stark initially splits with Bran going to the Godswood tree, with the Iron Born and Sansa and Arya heading to the walls of Winterfell to overlook the battle. But seeing the Night King's dark cloud of concealment sweeping in, about to neutralize the threat of dragons, Arya Stark first gets a hint that she might be dealing with a face of Death that she doesn't want to meet. The way her fear manifests, because she's a strong assassin who can have any blacksmith she wants, is to send Sansa down to the crypts with a dragonglass dagger and a "stick them with the pointy end" callback. Arya's palpable fear of the magic before her that hasn't been a factor since she returned to Winterfell, or maybe ever.
When we cut back to Arya after the Winterfell walls have been breached, she makes wight killing look easy with her split-apart, double tipped staff. As she spins and slices her way through an endless line of foes, the dead just keep coming. At one point, she has to do a sideways roll over a cluster of them just to get down a staircase. A wight slams her head into a wall, then Arya's fear starts to take hold once again. She ironically inspires the Hound to get back into the fight: at the exact moment she sneaks back inside Winterfell to hide from wights, Jurassic Park-style, Sandor Clegane was having a momentary freakout and froze.
The Hound and Beric end up going into the castle after Arya, and Beric takes several wight knives to the midsection while blocking the hallway so the Hound and Arya can get away. Beric brings them both back to Melisandre, and brings Arya out of her fear. It turns out that the last time Melisandre saw Arya she delivered an accurate prophecy. Is Arya a servant of the Lord of Light? Has she been put in the wrong category? As it turns out, probably. In the biggest surprise of the evening, Arya Stark ends up being the person responsible for taking out the Night King. In what X-Men fans will recognize as a modified fastball special, Westeros' tiniest assassin makes good on all her bravado and stabs the Night King with her Valyrian Steel dagger. The dagger that was supposed to kill Bran in the first season ended up being the dagger that saved Bran (and all of humanity).
Sansa went down to the crypts and had dramatic anchoring moments with Tyrion that we needed for the precious cutaways from the carnage of this episode. That is, until the crypt people came alive. (Told you.) Varys, Gilly, and Missandei are also around, but Sansa is the one with the wisdom in siege hiding (gained from surviving the Battle of the Blackwater under Cersei's wine-soaked guidance). It was nice to hear from Varys after he got sidelined last week, but the crypts end up being the least consequential thing in the episode, unless it was a way to set up a Sansa/Tyrion opposition to the upcoming Targaryen rule. Sansa said the relationship between them wouldn't work because of the Dragon Queen, but that's a small hurdle if Tyrion has to choose between Dany who likes burning Tarlys and Sansa Stark, who hasn't unfairly executed anyone yet.