Veteren British actor Jim Broadbent is joining the cast of Game of Thrones season 7. But who will he play?

Broadbent’s casting was revealed today by EW and is the first new face to join the epic array of characters aligning in Game of Thrones season 7.

Unfortunately for us fans, HBO is resuming their standard operating practice of offering as little information as possible. The network has not released the name of Broadbent’s character, revealing only that the role will be “significant.”

Given that Game of Thrones season 7 is now charging past the material established in George R.R. Martin’s A Song of Ice and Fire, there is very little chance of guessing exactly who Broadbent will be playing. It’s possible that the actor may have been cast in role of a maester (perhaps the mysterious Maester Marwyn) who Sam Tarly might encounter in the Citadel.

Other options include Mad King Aerys, perhaps appearing in further flashbacks. Less likely is the exiled Lord Jon Connington — though Connington’s elaborate book plotline seems to have been cut entirely from the HBO fantasy series.

Regardless of the specific role, Jim Broadbent represents a terrific addition to the cast of Game of Thrones season 7. The actor may be best known among nerds for his role as the Potions master Horace Slughorn in Harry Potter and the Half-Blood Prince.

In addition to many other roles, Broadbent won an Oscar for his supporting work in the film Iris, and also appeared in Brigit Jones’s Diary.

Meanwhile, the mystery surrounding Game of Thrones season 7 continues to ripen. On the technical side, the season is set to have fewer episodes and will air later (perhaps much later) in the year than the established spring premiere.

As for the story, well, Maisie Williams recently stirred up fans with her intense response to the scripts on Twitter, and now we have no idea what to think.

But hey, at least we know that Jon Snow isn’t dead.

Game of Thrones season 7 will air in 2017 on HBO.