The Stark family crypts have played an important part of the show in the past seasons possibly for a specific reason. With the Night King making its way to the North, it is easy to suggest that the long-buried Starks could also join the undead in Game of Thrones Season 8.
Season 1 Episode 1 featured the crypts after King Robert Baratheon arrived at Winterfell and he paid his respect to Lyanna Stark's grave. The crypt also appeared in several scenes in separate seasons, one when Jon Snow (Kit Harington) confronted and choked Littlefinger (Aidan Gillen) in Season 7 Episode 2.
Season 5 also featured the crypt where Sansa and Petyr Baelish talked about the time Rhaegar Targaryen gave Lyanna flowers and Sansa mentioned that Rhaegar kidnapped her aunt and raped her, which was what everyone in Westeros believed for years. Bran was also in the crypt when he had a vision.
Most of the important characters in the series have paid a visit to the Winterfell crypts for a very good reason, which fans believe has something to do with the oncoming threat of the Night King and his army of White Walkers.
The long-held question has been whether the dead Starks would rise from their graves, join the Night King, and turn into White Walkers themselves in Game of Thrones Season 8. The Night King has the power to bring back the dead and turn them into his allies as seen in previous seasons. He even turned Viserion into the undead in Season 7.
However, he would have to discover the crypts first and know about its existence to wake up the dead. This is where the speculations that Bran is the Night King connects. Then again, there have been a foreshadowing of the fate of the dead Starks in George R.R. Martin's books, and it has nothing to do with them turning into White Walkers.
"The Starks in the crypts, the Giant Stone & Bronze Bone Kings of Winter, along with their Giant Stone Direwolves, will rise, full of vengeance and rage, dark and strong to fight against the Others."
If taken literally, the Others would refer to the White Walkers. The dead Starks from the Winterfell crypts would rise and fight alongside their family in what could only be the biggest fight of all in Game of Thrones Season 8, which is the Night King battle.
