Doctor Who has not seen the back of the Master.

Or Mistress, whichever you prefer.

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Twelve and Clara didn't see the last of the regenerated baddie in "Death in Heaven." Instead, Michelle Gomez will return in season 9.

With season 8 barely in the ground, the actress' announcement comes shocking early for a series that puts a high price on secrecy. Tantamount to Marvel Studio's cone of silence, the BBC series usually waits until an episode airs to reveal such important casting news.

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Nevertheless, Gomez spilled the beans to Doctor Who Magazine.

"'Yes' is my answer. I'll be back," Gomez confirmed. "Can I say that? Am I allowed? If not... well, I guess we'll have to see how she's received..."

According to the actress, fans can expect more treachery from her character.

"Everything about making the Master the Mistress kind of ups the ante," Gomez said. "It makes everything that little bit more dangerous. It blows open this Pandora's box."

Find out more when Doctor Who airs its Christmas Special on Dec. 25. Click the video below to see a preview for the series' next episode.

Tags: Doctor Who television BBC BBC America