HBO has fleshed out the cast for their upcoming Game of Thrones prequel series, in addition to locking down a director for the pilot. At one point or another, HBO had as many as five different spin-offs set in the world of Westeros to help fill the void once the main series concludes, which is happening this year with season 8. But fans won't be without their fix for long, as the prequel series is moving along nicely, with the main cast now in place and the pilot seemingly in good shape.

According to a new report, Naomi Ackie (Star Wars 9), Denise Gough (People, Places and Things), Jamie Campbell Bower (The Mortal Instruments: City of Bones), Sheila Atim (Girl From the North Country), Ivanno Jeremiah (Doctor Who), Georgie Henley (The Spanish Princess), Alex Sharp (How To Talk To Girls At Parties) and Toby Regbo (Fantastic Beasts: The Crimes of Grindelwald) have all joined the cast as serious regulars. They join the previously announced Naomi Watts, who will be a series lead, and Josh Whitehouse, who will also have a major role. Details on who these new cast members will be playing are currently being kept under wraps.

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In addition to filling out the ensemble, it's also been revealed that S.J. Clarkson will direct the pilot episode for the still-untitled Game of Thrones prequel. Though, George R.R. Martin, who serves as an executive producer on the series and helped cook up the story, has been calling it The Long Night. Clarkson is known best for her work on shows like Jessica Jones and Dexter. Clarkson was also tapped by Paramount last year to helm Star Trek 4, but official developments on that project have been few and far between. If it does move forward as planned, Clarkson will be the first female director in the history of the Trek franchise.

But now, the future of Game of Thrones largely rests on her shoulders. What we know for sure is that the new series will take place thousands of years prior to the events of the main series. Jane Goldman will serve as showrunner. Goldman also wrote the pilot script, working from a story she cooked up with author and franchise creator George R.R. Martin. While firm plot details are being kept under wraps, Martin assures there will be no dragons and no Iron Throne.

Additional casting for the series is expected to be announced later this year before production gets underway. At the present time, HBO has only given the show a pilot order, but it's highly likely that it will be picked up to series. If that does come to pass, we'll likely see the Game of Thrones prequel arrive in 2020, since Game of Thrones season 8 is set to debut in April. We'll be sure to keep you posted as any further details on the new series are made available. This news was previously reported by The Hollywood Reporter.