Grant, who played Simon Bricker on Downton Abbey, has been cast in an undisclosed role, but will appear in a number of episodes, according to Variety. With Game of Thrones poised to go significantly off-book in the upcoming season, it's unclear whether Grant will play a character who's known to fans of the books or a newcomer to Westeros. With the recent addition of Freddie Stroma as Sam Tarly's brother Dickon, is it possible that Grant could be playing Sam's father Randyll?
Game of Thrones also recently cast Ian McShane in an unknown role.
Who do you think Grant will be playing? Share your theories in the comments!