Surprise! Doctor Who episode 7 finally reveals the show's Big Bad – and only one of your theories was right

Doctor Who told us way back in The Devil’s Chord that there’s always a twist at the end. In more than one sense, it was right.

Susan Twist – the actress who plays the mysterious woman seen across time and space this season – features heavily in ‘The Legend of Ruby Sunday’. But there’s also a surprise Big Bad reveal, one that has been the subject of countless theories and endless speculation online. So, who are they? And what does it mean for Doctor Who as it hurtles towards its season finale in ‘Empire of Death’? Let’s find out!

MAJOR spoilers for Doctor Who episode ‘The Legend of Ruby Sunday’ follow. You have been warned!

Throughout ‘The Legend of Ruby Sunday’, we – and the Doctor – remain focused on the mystery of Susan Triad (Susan Twist), head of S Triad Technology, as she gets ready to unleash a new something on the world.

The Doctor, as revealed way back in the First Doctor’s era, has a granddaughter called Susan. Unfortunately for those hoping for a family reunion, this was a red herring.

Instead, it appears Susan Triad was nothing more than an unwilling pawn for The One Who Waits. Her dreams were actually the appearances we’ve seen in previous episodes, hinting that she’s been inadvertently drawing the Doctor towards an unknown fate.

As the episode draws to a close, it’s revealed that the entity pulling the strings has wrapped itself into the fabric of the TARDIS. Then, it reveals itself: Sutekh.

Who is Sutekh?

The Big Bad? Sutekh. a play on Sue Tech – as it appears the Doctor was focused on the wrong piece of wordplay with the S.TRIAD/TARDIS conundrum. He’s even voiced once more by Gabriel Woolf.

Some may focus on the Egyptian dog-like appearance and immediately realize he’s bad news. But he also has a long, rich history across multiple pieces of Doctor Who media. And his return is worse than bad news for Ncuti Gatwa’s Time Lord.

For now, let’s stick with what’s said in the episode: As revealed by Harriet Arbinger (H. Arbinger, get it?), Sutekh is the "threefold deity of malice, mischief, and misery." He is the God of all Gods and the God of Death, standing above the likes of Toymaker (God of Games), Trickster (God of Traps), and Maestro (God of Music).

From here, Sutekh’s plan is revealed: the ‘gift’ Susan Triad was giving to the world is actually the touch of death, as brutally evidenced by one of Susan’s team crumbling to sand.

And that’s where we leave ‘The Legend of Ruby Sunday.’ The wider history of Sutekh, though, gives us a glimpse of what could come next.

First appearing in 1975’s The Pyramids of Mars, Sutekh is an Osiran alien who was trapped in a burial chamber in Egypt. Upon being awoken by an archaeologist, he sets about destroying the Earth and, beyond that, the rest of the universe. He is only stopped by the Fourth Doctor and Sarah Jane Smith trapping Sutekh in a time corridor, where he dies of old age.

Except, now he’s out. Wider Doctor Who media – including one comics story – reveals he escaped through bizarre means involving taking over his son’s body to force his release. We suspect that isn’t canon, however.

The show itself may yet have its own explanation to come, but our prevailing theory remains that David Tennant’s Fourteenth Doctor using superstition at the edge of the universe has allowed all manner of gods and tricksters to escape imprisonment (Neil Patrick Harris' Toymaker, of course, being the most prominent of them). It seems that the circle of salt in Wild Blue Yonder has also seemingly led to Sutekh’s return.

Doctor Who is streaming on Disney Plus in the US and BBC iPlayer in the UK, with new episodes being broadcast on Saturdays on BBC One.

For more, check out the new TV shows coming your way later this year.