'Doctor Who's Susan Twist mystery: Breaking down the clues and fan theories

Why are Whovians losing their collective cool over Susan Twist? Well, it's because the elderly English actress is popping up again and again on Doctor Who, and in a very timey-wimey way. 

Sure, all kinds of actors have appeared on the iconic series over its decades of television, sometimes more than once; one even got upgraded from Pompeii resident to Twelfth Doctor (Peter Capaldi). But there's something especially curious about Twist's appearances, as they've all come in a recent jumble. 

This collision of cameos has got fans theorizing all kinds of possibilities for what Season 14 showrunner Russell T Davies has up his sleeve. With the latest episode, "Boom," there are fresh clues to who Twist is really playing. So, let's pick through the appearances and the fan theories one by one. 

Susan Twist in "Wild Blue Yonder" 

This episode was the second of the 60th anniversary specials, which saw David Tennant and Catherine Tate reprising the roles of the Doctor and Donna respectively. In this adventure, the two are flung far into the future, where they are plagued by creepy doppelgängers of themselves. But Twist pops up before these freaky sci-fi events. FAR before. We're talking the opening sequence set in 1666 England. 

There, a dashing Isaac Newton (Bernard Cribbins) is on the brink of "discovering" gravity. On his walk to that fateful apple tree, he comes across Mrs. Merridew (Twist), a smiling, bonneted servant who tells him, "Don't come back until you find a really good idea, sir!" 

And that's it — so brief a moment, longtime Whovians took no notice of it on its own. 

Susan Twist in "The Church on Ruby Road" 

Moving along to "Special 4" — as Disney+ has labeled the Christmas special, "The Church on Ruby Road" — we find Susan Twist again in a role so brief, you may have well missed it. The first full episode featuring Ncuti Gatwa as the Fifteenth Doctor also introduces his new companion, Ruby Sunday (Millie Gibson). A foundling who lives in London, when Ruby's not searching for her birth parents or rescuing newborns from sky-sailing gremlins, she's in a band! 

On December 22, 2023, Ruby is playing keyboard at a Christmas concert at a bar. The Doctor is watching this performance, but he's not the only one. A long-haired woman yells out to the lead singer, "Give it some welly!" Then she requests a song, saying, "Can you do 'Gaudette'?" 

If you don't recognize that title, it may be because this rowdy concert attendee (also played by Twist) is referencing a Christmas carol that dates back to the 16th century. So despite her vaguely flower-child vibe, with her paisley jacket, long locks, and headband, her references go way, way back. 

Susan Twist in "Space Babies"

The premiere episode of Doctor Who Season 14, which sees Davies' return as showrunner, also brings Twist back — this time aboard an abandoned space station repurposed as a baby center. Well, sort of. 

The Doctor and Ruby discover the video logs of the crew, who left under protest of the company directive to abandon the babies. In one video, Twist pops up in a teal and gray crew uniform (giving Star Trek vibes), and introduces herself as Comms Officer Gina Scalzi before signing off in the year 21506. So from her first appearance to this one, Twist's face is popping up across 19,840 years. 

Susan Twist in "The Devil's Chord"

Released the same day as "Space Babies," episode 2 of Season 14 imagined a world without music, courtesy of the maleficent Maestro (Jinkx Monsoon). The Doctor and Ruby were hoping to take in the groovy mood of 1963 London — and more specifically the recording of the Beatles' first album at what would someday be known as Abbey Road Studios. But the beat is off. Music is bad, and people feel bad. And while Ruby and the Doctor are looking to give John Lennon and Paul McCartney a pep talk, a chatty cafeteria worker butts in with a bizarre interjection. 

They're buying tea in the studio's cafeteria, when Tea Lady (Twist!) offers two cups for half a crown. The pair are mock outraged by the price, and she responds, "Take it or leave it, sweetheart." The Doctor chides, "That is daylight robbery," and she replies, "That's me: Margaret Lockwood in The Wicked Lady. Now there was a woman. Statuesque!"

The Wicked Lady is a film from 1945, in which Margaret Lockwood played Barbara Skelton, a noblewoman who steals a friend's affluent betrothed and then hits it off with a rakish highwayman. So, that robbery connection explains why the character is referencing this movie. But what is Davies doing with this dialogue? 

Susan Twist in "Boom." 

Written by former showrunner Steven Moffat, this third episode of Season 14 takes Ruby and the Doctor to a war-torn planet, where weaponized Anglican priests are fighting the Kastarions — a seemingly invisible enemy. But these mysterious foes aren't the only trouble. An overenthusiastic AI ambulance can also be a major threat, as a recently blinded John Francis Vater (Joe Anderson) discovers when the ambulance non-consensually euthanizes him into a pocket-sized "casket" made of smelted marine.

And guess who is the face of the wickedly stoic ambulance? Yup. Susan Twist plays the AI ambulance created by the weapons manufacturer Villengard. 

What does all this mean? Here are some fan theories. 

Fan theory: Susan Twist is The One Who Waits.

In "The Devil's Chord," Maestro mentions being a part of a "Pantheon" of god-like beings, which we already know includes their father The Toymaker ("The Giggle," Special 3). But before the musical villain is gobbled up by an iconic piano, they cry out a warning: "The One Who Waits is almost here!" 

This suggests The One Who Waits is a part of this Pantheon, and maybe even its most powerful member. So, The One Who Waits may well be the Big Bad of Season 14. 

Perhaps this is why Twist is popping up again and again, with more screen time and more important parts to play in the Doctor's adventures. If she is The One Who Waits, is this how the powerful being is crawling closer and closer to the Doctor? Unbound by time and space as both the TARDIS and the Doctor are, this would make The One Who Waits a fearsome foe to be sure. 

Fan theory: Susan Twist is Ruby's birth mother. 

Something strange is going on with this Ruby Sunday. She's not your average Christmas-born foundling. "The Church on Ruby Road" showed that coincidence and bad luck follow her. "The Devil's Chord" revealed there's a song in her heart, but also something that scared Maestro enough to proclaim, "This creature is wrong!"

Even the Doctor has slyly given Ruby a TARDIS scan, though he hasn't shared with the audience what he found. 

There are other strange elements about her origin. The Doctor's memory of it changes, with her cloaked mother turning toward him in an apparent warning. And then there's the recurring snowfall, which follows Ruby into the TARDIS and onto the warring planet with no clear explanation. Could it be that Susan Twist is somehow a part of the Ruby Sunday mystery? What a twist that would be! 

Fan theory: Susan Twist is Ruby Sunday.

In "The Devil's Chord," the Doctor mentioned that in 1963, he was living in London with his granddaughter Susan on Totter's Lane. This aside slyly reveals to Whovians new and established that a character can cross their own timeline. And perhaps whatever Ruby really is allows her to do this, resulting in two actresses secretly playing the special companion. 

Alternatively, Davies might be pulling a Moffat move from Season 6, episode 10, "The Girl Who Waited." In that misadventure, an alternate version of Amy Pond is trapped in a resort planet for 36 years alone. Could it be that Susan Twist is playing an alternate reality version of Ruby Sunday? And could the title "The Girl Who Waited" be a clue that this alternate version might also be The One Who Waits? 

Fan theory: Susan Twist is... Susan Foreman? 

Back again to "The Devil's Chord," where the Doctor name-drops his granddaughter Susan but says he has no idea if she survived the Time Lord genocide. Ruby seems astonished he hasn't looked into this. But is it possible his granddaughter is looking for him? 

Susan Foreman was the first companion of the First Doctor when the show began in the 1960s, but she hasn't been a major part of the lore of the relaunched TV series until Davies brought her up in Season 14. Her role was originated by Carole Ann Ford, who has reprised the part in podcast adventures, most recently 2023's Doctor Who: Once and Future. So, you might well wonder, why would Davies recast her? Maybe bringing back Ford would give the game away too soon. 

With decades of lore to play with and all of time and space as his playground, Davies has fans in a tizzy over what the meaning of Susan Twist's curious recurring roles will be. But in "The Devil's Chord," he dropped a meta clue with the controversial final song number, "There's Always a Twist at the End" — as "Susan Twist" has always been in the end credits so far this season.

Perhaps this wasn't just a gleeful bit of song-and-dance spectacle, but Davies warning us to keep an eye on this actress. And if her last name is a clue, then perhaps her first name is as well. Perhaps this Susan Twist could be the new Susan Foreman, searching the whole of the universe and existence for her long-lost grandfather, The Doctor.

Only time (and more episodes of Doctor Who) will tell. 

How to watch: New episodes of Doctor Who drop every Friday night at 7:00 p.m. ET on Disney+, where available, and simultaneously at midnight on BBC iPlayer in the UK. The season finale airs June 22.