Mystery solved: the professor with the dragonglass in the Citadel.

When "Game of Thrones" season 7, fans began speculating which character the veteran actor might play. Well, guys, many of you were right: Broadbent confirmed to Screencrush that he's playing a maester in the Citadel

"I'm a maester, an archmaester. I'm an old professor character," he said. "I did five episodes. I did sort of one major scene in each episode."

While Broadbent did not reveal his character's name, he did slip that he shares scenes with Samwell Tarly, who recently arrived at the Citadel to train as a maester. Those clues indicate that Broadbent does, indeed, play Marwyn, as fans have guessed.

In the books, after Archmaester Marwyn hears Sam's story about what he's seen beyond the Wall — the White Walkers — he leaves to find Daenerys Targaryen. In the show, she is on a ship bound for Westeros, so perhaps this meeting will take place sooner than we think.

"Game of Thrones" season 7 premieres sometime this summer on HBO.

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