Who is The One Who Waits in Doctor Who? All the best theories

This new era of Doctor Who is building to one heck of a big bad. In fact, it looks like it could be the biggest of big bads in the show's history — enough to make a Cyberman swallow its voice modulator in fright. This is the mysterious One Who Waits.

We first heard about the One Who Waits in the final 60th anniversary special, The Giggle, last year. The Toymaker said there was "only one player I didn't dare face" in a game — The One Who Waits. Speaking cryptically, he said: "I saw it hiding, and I ran."

The One Who Waits was mentioned again in the episode The Devil's Chord, in which the Toymaker's defeated child, Maestro, warned the Doctor that "the One Who Waits is almost here".

It seems we're only a few weeks away from finding out who this terrifying being is, which leaves us plenty of time to speculate on the identity of Doctor Who's biggest and baddest villain ever.

The Rani

Doctor Who fans will know by now that every mysterious, secretive character in the show will be revealed as The Rani. The renegade Time Lord's name pops up at least once a year in connection to at least one of the Doctor Who mysteries swirling around and, like a stopped clock, those theories are bound to be correct eventually.

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The late Kate O'Mara's delightfully over-cranked performance as the villain in two 1980s serials — as well as a Children in Need special in 1993 — made the character a fan-favourite. She was a Time Lord scientist who thought nothing of experimenting on humans.

Given that viewers have been waiting for her ever since the show returned in 2005, it would be fitting for us to learn that The Rani has been waiting too — just to pick the perfect moment.

Fenric

The idea of the One Who Waits as an ancient being living outside time has inspired some Whovians to declare that Fenric will be revealed as the mysterious villain. Just like The Rani, Fenric was an adversary of the Seventh Doctor, appearing as one of the most significant enemies of that era.

Fenric's history describes him as being a force of pure evil, surviving from the primordial clash of energies that birthed the universe. He's certainly got a level of power to spook entities even as strong as Toymaker and Maestro. There's also a connection with games, given his battles with the Doctor over chess problems in the 1989 story The Curse of Fenric.

A lot of puzzle pieces seem to come together around Fenric as the identity of the One Who Waits, so it's no surprise that he's one of the most popular theories.

The Trickster

The Trickster would be an interesting choice given that he has only previously appeared on screens in the noughties spin-off series The Sarah Jane Adventures. Of course, Russell T Davies created that series and had a big say in its creative direction, so The Trickster — who even collided with the Tenth Doctor in that show — would allow him to bring more of his old extended universe into this new era.

Much like the "legions" we've heard mentioned around the Toymaker and the One Who Waits, The Trickster was part of a group known as the Pantheon of Discord. With a truly terrifying faceless appearance, he's an immortal entity with a lust for chaos — exactly the sort of character who'd be connected to Toymaker and Maestro.

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We also know that Trickster has the power to manipulate the timelines of individuals, which could explain some of the strangeness around Ruby Sunday. Perhaps the Trickster was the "mother" who appeared on Ruby Road on that fateful Christmas.

Mrs Flood

When you cast someone as famous as Anita Dobson in Doctor Who, they're going to get longer than a few minutes of screen time. Ruby Sunday's mysterious neighbour showed up in the Christmas special and, in the enigmatic final moments, revealed that she knows what a TARDIS is.

Read more: So, who is the mysterious Mrs Flood in Doctor Who? (Cosmopolitan)

Other than that, we don't know anything about Mrs Flood, who she is, or what she wants. But if you're looking for someone who waits, then the elderly lady patiently sat outside the house next door to the Doctor's new companion is a prime contender.

The Valeyard

It's a pretty common trope in Doctor Who that the worst villains tend to represent some element of the Doctor himself. After all, he's one of the most powerful beings in the universe. Nowhere has this been clearer than with The Valeyard — a personification of all of the Doctor's darkest traits. Valeyard appeared in the ambitious Sixth Doctor arc The Trial of a Time Lord, serving as prosecutor in the Doctor's trial.

There have been references to The Valeyard throughout the modern series of Doctor Who, with the threat of what he might become serving as a sort of corrective to keep the Doctor on the straight and narrow. But perhaps there's some pocket of the Doctor's worst side sat at the edge of the universe, just waiting.

The Beast

When it comes to big bads, they don't get much bigger than the Devil himself. The Tenth Doctor faced up to the Beast in the 2006 episode The Satan Pit. That story culminated with the Beast jettisoned into a black hole, but a force that powerful could well be hiding somewhere on the fringes of the universe.

People tend to think this part of Davies' era as Doctor Who showrunner was a bit goofy and, certainly, The Beast never seemed like as big a threat as he probably should've done. However, with this level of build-up and perhaps a less cartoonish form, he could be a real match for the Doctor.

Susan Foreman

This new era of Doctor Who is desperately seeking Susan. The Doctor's granddaughter has been name-checked and referenced as an Easter egg several times in recent episodes, even though we haven't seen her since the 1983 episode The Five Doctors and the 1993 Children in Need special. Carole Ann Ford played the character in the 1960s, when she was the main companion of William Hartnell as the First Doctor.

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As for the new series, the actor Susan Twist has been popping up in different roles throughout the recent episodes — most recently as the "ambulance" in Boom. She's called Susan for real? That's too neat to be a coincidence.

But does this mean Susan will be revealed as the villainous One Who Waits? Well, perhaps not. But it's a safe bet that Susan will be a factor in the way this series plays out. She could be a surprise ally. She could be Ruby's mother. She could be the One Who Waits. Or she could be any combination of those things.

After all, there's always a twist at the end.

Doctor Who is streaming on BBC iPlayer, or on Disney+ outside of the UK