Game Of Thrones' Maisie Williams gives a mysterious performance alongside Peter Capaldi in new Doctor Who season 9 trailer

She already stars in one of the world's biggest TV shows, Game of Thrones, but it looks like Maisie Williams is about to conquer another TV phenomenon. 

Starring in a guest role, the 18-year-old actress makes a cryptic appearance in the season nine trailer for sci-fi favourite Doctor Who, which was debuted at Comic-Con in San Diego, California on Thursday. 

Viewers are given their first glimpse of Maisie as she engages in a puzzling exchange with The Doctor, played by Peter Capaldi.

Scroll down for trailer 

Mysterious: Maisie Williams made a cryptic appearance in the season nine trailer for Doctor Who, which was debuted at Comic Con in San Diego on Thursday

Mysterious: Maisie Williams made a cryptic appearance in the season nine trailer for Doctor Who, which was debuted at Comic Con in San Diego on Thursday

In a scene that is left until the very end of the explosive trailer, Capaldi watches Maisie unmask herself in astonishment before asking, 'You?' 

'What took you so long old man?' the actress replies with a smirk.    

The role will no doubt come as a welcome surprise for fans of both Doctor Who and Game of Thrones, with the latter seeing the teen star as revenge-seeking tomboy Arya Stark.

Viewers were given their first glimpse of Maisie as she engaged in a puzzling exchange with The Doctor

Viewers were given their first glimpse of Maisie as she engaged in a puzzling exchange with The Doctor

Shocker: In a scene that is left until the very end of the already-explosive trailer, Peter Capaldi looked on in astonishment as Maisie - whose identity we are yet to discover - lifted her mask

Shocker: In a scene that is left until the very end of the already-explosive trailer, Peter Capaldi looked on in astonishment as Maisie - whose identity we are yet to discover - lifted her mask

Cryptic: The teen will appear in two episodes of Doctor Who's ninth season

Cryptic: The teen will appear in two episodes of Doctor Who's ninth season

It's been announced that Doctor Who will return to TV screens with a 'new hunger for adventure' next time around.

The ninth series of the iconic sci-fi programme will see Peter Capaldi reprise the role of the Time Lord and he's given fans of the show an idea as to what they can expect from the much-anticipated new season.

He shared: 'Soaring through all of time and space, series nine sees the Doctor throw himself into life with a new hunger for adventure. 

Breaking out: Maisie as Arya Stark in hit HBO series Game of Thrones

Breaking out: Maisie as Arya Stark in hit HBO series Game of Thrones

'The Cosmos is there for the taking, thrilling, epic and enticing, and his to play in.

'But he's almost reckless in his abandon. It's almost like he's running from something, something that if it ever catches him will turn his life upside down.'

Meanwhile, Peter recently revealed he is desperate for Jenna Coleman to stay in Doctor Who.

Bidding farewell? Jenna Coleman has been surrounded by claims she is to leave the franchise and pursue a career in Hollywood

Bidding farewell? Jenna Coleman has been surrounded by claims she is to leave the franchise and pursue a career in Hollywood

The actress plays his on-screen companion Clara Oswald and is often linked with a move away from the show - but Peter, 57, is eager for her to stick around.

He said: 'Jenna continues to deliver a complex and funny performance that marks her out as one of the best companions ever.

'Will these be her last shows? I hope not.'

Doctor Who season 9 will hit screens on September 19. 

He's back! Peter will reprise the role of heroic timelord Doctor Who in the BBC sci-fi

He's back! Peter will reprise the role of heroic timelord Doctor Who in the BBC sci-fi

Peter's angels: The Scottish actor attended Comic Con with co-stars Jenna Coleman and Michelle Gomez

Peter's angels: The Scottish actor attended Comic Con with co-stars Jenna Coleman and Michelle Gomez

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