Everything you need to know about the Zygons

From their weird abilities to their appearance in the Day of the Doctor, we're suckers for the shape-shifting Doctor Who villains


There’s a lot of love among Doctor Who fans for the Zygons yet they’ve only appeared in two major stories – until now…


New two-parter The Zygon Invasion/Inversion sees the return of the shape-shifting aliens, so what better time to remind ourselves where they came from, what they want and what they’re capable of…

First appearance – Terror of the Zygons

Sarah-Jane Smith (Elisabeth Sladen) is attacked by a Zygon in Terror of the Zygons

Hailing from the destroyed planet Zygor, the Zygons first appeared in 1975 serial Terror of the Zygons where – together with a dangerous cyborg sea monster called a Skarasen (better known to humanity as the Loch Ness monster) – they faced Tom Baker’s Fourth Doctor and UNIT. 

Eventually the Zygons were foiled (after a bit of classic mistaken identity fun), and apart from a few appearances in radio and Doctor Who novelisations, the shape-shifting suckers didn’t appear in Doctor Who again for over 30 years…

Their years in the shadows

Technically, the next time the Zygons interacted with the main Whoniverse was in 2010 episode The Pandorica Opens, where the amphibious villains were said to be part of the alliance (along with Daleks, Cybermen, Sontarans, Autons and more) that trapped the 11th Doctor (Matt Smith) in the Pandorica to try to save the universe.

They then made an appearance (though not in Zygon form) in 2012’s The Power of Three, when the Doctor (Smith again) accidentally took companions Amy and Rory on a romantic getaway to the Savoy hotel which turned out to be a front for a Zygon spaceship. Imagine the TripAdvisor rating.

The Day of the Doctor

The Zygons finally returned in a big way for this 50th anniversary episode (perhaps due to the involvement of former Tenth Doctor and avowed Zygon fan David Tennant). The homeless aliens attempted to invade planet Earth once more by landing in the 16th century and putting themselves into suspended animation in some paintings (it made sense at the time, OK?)

During the course of their invasion the Zygons made duplicates of UNIT’s Kate Stewart (Jemma Redgrave) and Osgood (Ingrid Oliver), resulting in a stand-off as the real Kate attempted to detonate a nuclear warhead under the Tower of London, which would have killed everyone present and destroyed much of London.

To avoid this unpleasant outcome, the Doctors (David Tennant, Matt Smith and John Hurt) temporarily wiped the memories of both humans and Zygon duplicates, forcing both parties to agree to a perfectly fair peace treaty as nobody knew which way to skew it. 

All’s well that ends well – until something goes wrong. But you’ll have to watch the Zygon Invasion to learn about that…



The Zygons have a few tricks up their suckery sleeves, including the ability to fire an electric discharge from their hands that can stun or disintegrate anyone it touches, and a nice line in slimy advanced technology (look out for the Doctor “titivating the fronds” of a “Zygon control polyp” in The Zygon Invasion).

Still, their best party trick is their ability to shapeshift, which over the years has allowed them to take the form of any other living thing (whether it be human, alien or horse). 

The natural Zygon form

The rules of this ability have changed a little over the years – originally Zygons had to keep those they were mimicking in a special receptacle and renew the bodyprint every couple of hours, but by the time of The Day of the Doctor the subjects only needed to be alive for the Zygons to copy them. In the new episodes their abilities have actually evolved even further, but you’ll have to watch to see exactly how.

Side note: apparently a Zygon who can no longer transform is called a Zynog, so that’s fun.

What do they want?

Well, this is a little more complicated – originally the Zygons weren’t necessarily out to exterminate other races like the Daleks, or convert others to their cause like the Cybermen. They weren’t even in it for the giggles like the Sontarans – they were just looking for somewhere to live after their planet was destroyed, and saw conquering the Earth as a good way to achieve that.

Once they were peaceably settled among the human race (after the Day of the Doctor) it seemed like everything was sorted for them – unfortunately, not all the Zygons were quite so happy with this deal, resulting in the surprising events of this week’s episode (which we won’t spoil by going into in too much detail here).

But what do they want NOW? Apparently, it’s Truth or Consequences – and we won’t say any more than that.


Doctor Who: The Zygon Invasion is on BBC1 tonight (Saturday 31st October) at 8:15pm