The cast of the third season of House of the Dragoncontinues to grow. Deadlinereports that Tom Cullen, Joplin Sibtain, and Barry Sloane have joined the cast of the prequel series that follows the rise and fall of the Targaryen dynasty. The world of Game of Thrones will continue to expand, as principal photography for the new episodes of House of the Dragon continues. As filming goes on, casting announcements can be expected from the massive production HBO has been developing since the Game of Thrones television adaptation came to a close. The most powerful family in all of Westeros is expected to return to the screen at some point next year.