The prequel series to HBO's。 Game of Thrones。has its first star: Naomi Watts. 。

Watts has signed on as "a charismatic socialite hiding a dark secret," though all other details, including her character's name, remain a mystery. The casting brings to an end to what Deadline describes as the "lengthy negotiations" that led to the show's first cast member signing on.。

SEE ALSO:6 people who might show up in the 'Game of Thrones' Age of Heroes prequel 。

As we previously learned, the prequel series is set thousands of years before the events of。 As we previously learned, the prequel series is set thousands of years before the events of 。Game of Thrones。

. It unfolds during the late stages of Westeros's so-called "Age of Heroes," a time that featured -- among other things -- humanity's first clash with the White Walkers.。Mashable Top StoriesStay connected with the hottest stories of the day and the latest entertainment news.Sign up for Mashable's Top Stories newsletter。By signing up you agree to our Terms of Use and Privacy Policy.
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。 Thanks for signing up! 。Watts is the first and only cast member to be revealed so far. 。

Game of Thrones。

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creator George R.R. Martin is involved as an executive producer, alongside Jane Goldman, also the prequel's showrunner. 。

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It's not clear when the series pilot will be shot or when anyone outside of HBO will get to see it. But given the topsy-turvy nature of Hollywood creative development, where projects can disappear in an eyeblink, this casting news is a good sign that HBO is moving forward with the prequel. 。

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