Maisie Williams will make a third appearance in Doctor Who series nine.
Writer Sarah Dollard has confirmed that the Game of Thrones star will appear in Dollard's episode 'Face The Raven'.
'Face The Raven' is the tenth episode of series nine. It will also feature the return of graffiti artist Rigsy and will be directed by Justin Molotnikov.
Dollard commented on her Twitter that Williams' return has been "really difficult not to tell everyone".
She was speaking at the MCM London Comic Con earlier as part of a panel with Steven Moffat, Mark Gatiss and Rachel Talalay, who will be directing the series nine double-bill finale.
Moffat has insisted, though, that Williams is not the new companion.
In the show, Williams plays Viking girl Ashildr and viewers saw her make her second appearance on last night's episode 'The Woman Who Lived'.
Her character was made immortal in 'The Girl Who Died'.
Earlier this week, Williams had hinted at a return for her character later in the series.
"I'm hoping she comes back," she said. "Everyone's been asking if she comes back. I hope so, but I have no idea.
"I know they've had characters similar to Ashildr that have returned in future episodes and series, so we'll see. I think there's a good chance!"