Given that Ed Sheeran's latest album is breaking streaming records and "Game of Thrones" has likewise broken records as the TV's most illegally downloaded series, Sunday's revelation that the "Divide" singer-songwriter will be guest-starring in the HBO hit could literally break the Internet.
According to Vanity Fair, Benioff and Weiss told the panel that they had been trying to recruit Sheeran to appear on the series for years in order to surprise Williams, who is a huge fan of the musician's work and a friend of Sheeran.
That wasn't the only big reveal from team GoT at SXSW, though.
During the panel, they also confirmed the final season, season eight, will only be six episodes, making it the shortest yet.
Both Coldplay's Will Champion and Snow Patrol's Gary Lightbody have been on the show. Benioff and Weiss were joined by Maisie Williams and Sophie Turner - a.k.a. Arya and Sansa Stark - who served as moderators for the panel.
Of course, with "Game of Thrones", you never know if he's actually hinting at the death of another Stark. When Williams asked the two which character they wished they could bring back to life, they said Hodor would get his own spinoff sequel, a multicam sitcom. This season they finally got him, they said.
Don't forget - Game of Thrones will premiere this summer on HBO.