After that shock Doctor Who reveal, Russell T Davies teases that one more villain is "lying in wait, exactly 160 years away": "Stand by! This is the big one!"

Doctor Who showrunner Russell T Davies says season 2 is ending with the introduction of a brand new villain - to round out the Unholy Trinity.

"NEXT WEEK: Wish World. Enemies old and new unite as the Doctor faces the Unholy Trinity. This is only two thirds of the Trinity, the two Ranis count as one, cos I say so," Davies wrote on Instagram. "The third is lying in wait, exactly 160 years away. So stand by! This is the big one! First of a two-part finale! The Pantheon is stirring. Old friends are helpless. And the whole of reality is in danger as we hurtle towards May 24, in the Ranis' most terrifying experiment yet."

At the end of Doctor Who season 2 episode 6, it was revealed that Mrs. Flood (Anita Dobson) was actually Rani (originally played by the late Kate O'Mara), a renegade Time Lord and amoral biochemist - who then split herself in two (with her other half being played by Archie Panjabi). Some fans thought the Unholy Trinity would consist of the two Ranis and Jonah Hauer-King's Conrad, but it looks like a brand new villain is on the way.

There are just two episodes left of season 2 (which is technically series 15, in case you're confused). "Wish World" is set to air on May 24, with The Reality War arriving on May 31.

Doctor Who is currently airing on BBC iPlayer and BBC One in the UK. It's also streaming on Disney Plus worldwide. For more, check out the Doctor Who season 2 release schedule.