What's more badass than a gigantic dragon that breathes fire? How about a much, much bigger one that breathes ice? Ice dragons are legendary creatures, never before seen in either Game of Thrones or the book series it's based on, but some fans are speculating they'll be making an appearance soon. Given that possibility, some fans may find themselves wondering more about these creature and the logistics of what they are. For instance, are ice dragons different from wights on Game of Thrones? According to some theories, yes — but that's only some of them.
It's been kind of a confusing time for book-readers such as myself. I know I shouldn't think of the books and the show as the same thing — they're clearly not — but after so many years without a new book, it's hard to keep from projecting a little. Many people who haven't read the books will by now be familiar with Lady Stoneheart and the valonqar and three-headed dragon prophecies — major elements of the books that have yet to make it into the show, but which are really fun to speculate on.
The ice dragons are in the same vein. They have only been mentioned a handful of times in the books, and never once in the show, but it's such a cool idea that it's entered the world of Game of Thrones.
In A Song of Ice and Fire, the ice dragons are "made of living ice, with eyes of pale blue crystal, vast translucent wings, and breath of cold." "Ice Dragon" is also the name of a constellation that points towards the north. Unlike the fire-breathers, they're only considered legendary; there has never been any documented sighting of an ice dragon in that world.
So, given that they haven't gotten much attention in the books, why would ice dragons warrant our consideration? Due to the vast amount of time book fans have had since ASoIaF's last installment came out six years ago, everyone's had the chance to reread and rewatch, to look for the tiniest clues as to what might be coming in both the books and the show. And the theories can get pretty out there. Some fans believe that one of Dany's dragons will die and be reanimated in classic wight-fashion by the Night King. Many think that reanimated ice dragon will be Viserion, since he has the most horrible namesake.
The problem with this theory is that, according to canon, the ice dragon is known to be bigger than regular dragons. The theories really go in all directions: Some fans believe that there's an ice dragon sleeping within the Wall, and that it waking up is what will bring the Wall down. Going along with the theory that the White Walkers are actually the good guys, there's the theory that the ice dragon will be a force for good, to be ridden by Jon Snow against Daenerys.
Finally, many fans think the term ice dragon is merely metaphorical, referring to Jon himself — since Jon comes from Stark and Targaryen stock. Redditor LiveVirus has an extensive history and analysis of ASoIaF's ice dragons for your perusal.
Bottom line, though, is that an ice dragon on Game of Thrones could very well show up by the end of Season 7. And if it does, there's no telling how this war of fire and ice will shake out.