Stark? Lannister? Baratheon? Targaryen? Hodor? Who will sit on the Iron Throne? It's been set up as the big plot, the mystery and endgame, of Game of Thrones since the very beginning, through the War of the Five Kings to all of the scheming of characters such as Varys and Littlefinger. It doesn't matter. None of it does, really, in the grand scheme of things. The Houses may have their rivalries and their wars, but something bigger is looming. To many characters within Westeros it's simply a myth, a tall tale told to scare small children. We know different. The Others, or the White Walkers, are coming. We have already seen a few glimpses of their devastating power, most recently and notably in Season 5's stunning Hardhome, but the feeling is we've only began to scratch the surface of what they're capable of. As the series progresses closer towards its end, they're set to play a bigger part. Indeed, if many theories are to be believed, then they'll be the cause of the total destruction of the Seven Kingdoms, or at least the enemy to be defeated in one final, epic battle. Despite this prominence, they remain something of a mystery, legendary figures rather than factual ones. So, what do we really know about them?