'Game of Thrones' Three Heads of the Dragon Prophecy: What It Means

The chilling "Game of Thrones" season 7 finale is still stirring conversation about its amazing revelations. One of the big questions raised by the closing episode is whether the Three Heads of the Dragon prophecy is still relevant, or if it requires a new interpretation. Spoilers for "Game of Thrones" season 7 follow.

The prophecy in question is uttered in a passage from "A Clash of Kings," the second book in George R.R. Martin's "A Song of Ice and Fire" series that HBO adapted as "Game of Thrones." At one point in "Clash," Daenerys Targaryen enters the House of the Undying, where she has dreamlike visions, including one of her brother Rhaegar attending to his newborn son Aegon. Rhaegar's eyes meet Dany's and he says, "There must be one more. The dragon has three heads."

"Game of Thrones" did its own version of the House of the Undying sequence that was unique to the show, rather than presenting the same visions that Daenerys experienced in the novel, notes Thrillist. The show left out the part where Dany saw Rhaegar and heard his prophetic words.

But if the prophecy turns out to be an important plot point in the books, then it very likely means that the second and third heads of the dragon will play roles in the HBO series. Given that in season 7, Jon Snow gained the trust of Dany's dragons and was revealed to be the son of Lyanna Stark and Rhaegar Targaryen... it would make perfect sense for Jon to be the second of the three heads and become the rider of the dragon Rhaegal, who is named after his father.

The identity of the third head of the dragon remains a mystery, although there are several compelling theories. One long-running fan theory states that Tyrion Lannister is the third head and is actually a Targaryen by birth. Proponents of this theory point to the season 6 episode "Home" where Tyrion successfully approaches and frees the dragons Rhaegal and Viserion as evidence that he is of the Targaryen bloodline.

But the "Game of Thrones" season 7 finale revealed an undead Viserion whose rider is none other than the Night King. That makes it highly unlikely that Tyrion will become a dragon rider with Viserion as his mount.

Vanity Fair suggests that Bran Stark may be the one to fulfill the prophecy. As the Three-eyed Raven, Bran has the ability to "warg," or possess the mind and body of another creature. Perhaps he will take control of the undead dragon and turn him against the Night King in battle, completing the three heads of the dragon.

Yet another theory comes from Popsugar, which predicts that Jon and Dany will bear a child. Their child will be the third head of the dragon and also fulfill another prophecy that foretells the Prince That Was Promised.

For now, it is too early to say which of the theories will come to pass, if any. But one thing to keep in mind is that the prophecy may not necessarily be a reference to dragon riders. It may mean that there are three Targaryens to watch out for in "Game of Thrones." Two have already been revealed, but the third remains in the shadows. Tyrion appears to be the likeliest candidate for the third Targaryen. He might not become a dragon rider, but Tyrion can still turn out to be the third head of the dragon after all.