‘Doctor Who’ Sutekh reveal: Meet The One Who Waits.

Doctor Who fan and showrunner Russell T Davies wanted to bring back Sutekh, a classic villain from the Tom Baker era of the show. So he invented “Sue Tech” — a.k.a. tech CEO Susan Triad, the final form of Davies’ season-long Susan Twist mystery. That’s what millions of other Doctor Who fans discovered in the final minutes of the show’s tense pre-finale episode “The Legend of Ruby Sunday.”

With the distraction of trying to discover Ruby’s mother, a red-herring anagram (S TRIAD, too obviously TARDIS) and the bombshell question of whether Susan Triad was a regeneration of his granddaughter Susan, the Doctor (Ncuti Gatwa) failed to notice one of his ancient and most powerful enemies has wrapped himself around the TARDIS — a machine this villain has manipulated before.

Welcome back Sutekh, a fan favorite Doctor Who villain who previously only appeared in one story nearly 50 years ago, and now also the Jeopardy! question to the answer “this character was revealed to be The One Who Waits.”

Who is Sutekh?

Sutekh the Destroyer is the villain of the 1975 story “Pyramids of Mars,” an iconic Tom Baker tale from one of the show’s most gothic horror-filled seasons. And it didn’t get more 1975 gothic horror than an ancient Egyptian god (Sutekh, also known as Set) who turns out to be a genocidal alien imprisoned on Earth by his people, the Osirans.

Sutekh was kept in check by signals from a radio beacon in a pyramid on Mars. How those signals worked exactly, especially given that Mars is sometimes on the opposite side of the sun, was never explained. Anyway, Sutekh was released from his tomb by a blundering British Egyptologist, Dr. Marcus Scarman (Bernard Archard), in 1913.

Aiming to destroy all of creation, Sutekh inhabits Scarman, and eventually mind-controls the Doctor into taking the TARDIS and Scarman to Mars to destroy the beacon. (It’s implied that Sutekh was powerful enough to draw the TARDIS to him in the first place.) Sutekh succeeds in destroying the beacon— but then the Doctor pulls a fast one by trapping Sutekh in a “time corridor” during the radio transmission gap between Mars and Earth.

A Time corridor? Not quite the Time Window that UNIT HQ has in “Legend of Ruby Sunday” — something we’ve seen before in “The Girl in the Fireplace” and “The Day of the Doctor” — but close enough. Oh, and there’s another UNIT connection to “Pyramids of Mars” — much of which takes place in an Edwardian country house that will one day be the HQ of … UNIT.

Baker’s Doctor estimates that Sutekh ages 7,000 years in the time corridor; we’re told that he dies there, but we never see the body, a fact that has already allowed Sutekh to crop up Lazarus-like in audio adventures, comics and novels.

‘The Pyramids of Mars’ is a theme this season.

If you’re feeling like the Sutekh connection came completely out of left field, note that Davies has referenced this exact story once this season already. Like “Sue Tech,” the 1975 story has been hiding in plain sight.

In “The Devil’s Chord,” Davies lifted the scene where Ruby Sunday sees the future apocalypse if they don’t stop the Maestro directly from “Pyramids of Mars.” In the 1975 story, Sarah-Jane Smith (the late, great Elisabeth Sladen) is shown her own blasted future if Sutekh wins.

Something else that’s been hiding in plain sight, on multiple sets and costumes, so often you’ll just have to go back yourself and look? Triangles, a.k.a. triads, a.k.a … pyramids.

The corporate logo on the ambulance in “Boom!”? Triangular. The sconces in the big music room during the “Devil’s Chord” climax? Triangles. Jinkx Monsoon’s hair and outfit for most of that episode? Multiply triangular. (And yes, a triad is another name for “chord.”)

The thing that Rogue and the Doctor trapped the Chuldur on in “Rogue”? Huge triangle.

We may have seen Sutekh in satanic form.

One other thing noted in “Pyramids of Mars” about Sutekh: The murderous swathe he cut through the universe left him so reviled that some cultures called him “Satan.” (This is where the story’s connection to Earth mythology ends, because in our world Set/Sutekh and Satan are figures with completely unconnected origins).

Nevertheless, we have seen Satan in Doctor Who — specifically in Davies’ first go-round as showrunner. “The Satan Pit” had the Doctor (David Tennant) meeting the titular devil. Satan attempts to escape to Earth via a spaceship crew, forcing the Doctor to consider sacrificing Rose (Billie Piper).

No connection between that Satan and Sutekh has been established, beyond the fact that they were both voiced by Gabriel Woolf (who reprises his role as Sutekh in “Legend of Ruby Sunday” at the grand old age of 91 — providing hope for everyone who thinks Carole Ann Ford, 83, may yet return as the Doctor’s granddaughter Susan.)

With that connection, though, Davies now has every excuse to tie that highly popular story to his current big bad. After all, Sutekh has been around for a long, long time — plenty of time to take plenty of forms and fall into plenty of traps.

What will Sutekh do next?

Arguably, the name of the finale itself was a spoiler hiding in plain sight. “Empire of Death” sounds like exactly the kind of outcome Sutekh intended to bring about: the end of all living things who could oppose him (everything and everyone, basically).

It’s also worth noting that the logo used when revealing the season’s episode titles put “Empire of Death” in the place of “Police Box” at the top of the TARDIS. Sutekh has control of the Doctor’s machine now, just as the Toymaker and the Maestro both briefly had it. But Sutekh is so powerful, he even scared the Toymaker (who first mentioned him as The One Who Waits).

What could a God of Death do with a time and space machine that contains all the power of a black hole? “All creation shall fall into dust and ruin,” announced Harriet Arbinger at the close of “The Legend of Ruby Sunday.” Sutekh ended the episode promising the Doctor “and all in your vile incessant universe … Sutekh’s gift of death.”

In other words, death comes to everyone and everything, everywhere, all at once. How does the Doctor get us out of that? Is it possible that the Doctor’s granddaughter is going to save the day after all? Could there, in other words, be one final Susan twist at the end?

How to watch: New episodes of Doctor Who drop every Friday night at 7 p.m. ET on Disney+, where available, and simultaneously at midnight on BBC iPlayer in the UK. The season finale airs June 22.