I think Brienne actually killed the Hound when they fought and the Lord of Light brought him back, like he brought back Jon Snow and Beric.
If that's true, then are all Hound, Jon, Beric etc. ultimately reanimated corpses, also know as wights, but re-animated by fire, not ice like the White Walkers.
Also, since all three would be fighting against White Walkers together, does it mean the ultimate battle is going to be between wights — corpses reanimated by ice (White Walkers) and fire (Jon Snow, Hound etc.)
What do you people think?