So far on Game of Thrones, dragons have been characterized by one thing above all else: fire. Their ability to spew flames at anyone who crosses their mother is essentially their defining quality. But that may be subject to change now that Viserion has undergone a transformation, turning from a fiery living dragon to an icy undead one. But is Viserion the only ice dragon on Game of Thrones?
As far as viewers know, he is. Viserion is the only ice dragon that has appeared on the show, though the full extent of his ice dragon capabilities have yet to be explored. In the world of Westeros, ice dragons are supposedly able to breathe cold air instead of hot, freezing anything and everything in their path. They've never shown up in the flesh, but they've been figures of legend for centuries in Westeros.
And many fans of George R. R. Martin's series have wondered about the possibility of ice dragons turning up somewhere down the line. They haven't appeared in the novels either, but they have been mentioned many times before. Martin also wrote a novella called The Ice Dragon that is unconnected to the A Song of Ice and Fire universe, though some have nevertheless taken it as a hint of things to come.
In the novella, a young girl's friendly ice dragon pal is killed and melts, forming a lake. Despite the different fictional worlds, readers have come up with a few theories about how an ice dragon will make itself known in Westeros. Some speculated that a notably chill lake by Winterfell is actually a slumbering ice dragon. Others have wondered whether an ice dragon is waiting within the Wall, counting down the days until it crumbles and the dragon is freed. Either way, those ice dragons are definitely catching up on some sleep; they're not zipping around like Viserion will presumably be doing soon.
There are some differences between Viserion and a normal ice dragon, however. He is undead, whereas ice dragons are living creatures who just so happen to be on the colder side of the dragon spectrum. If they were as extinct as their hotblooded cousins, then presumably any left alive are still dormant. However, now that Game of Thrones has made it clear that ice dragons can be created by White Walkers as well, it seems like the only way to get more of them would be to target another of Dany's living dragons.
Fans probably couldn't take losing a second dragon so soon after the first, so hopefully the Night King and his people will steer clear of Drogon and Rhaegal. With one dragon, his army is formidable, but with any more he'd be damn near unstoppable.