Kate Stewart

Inversion of the Zygons
Kate Stewart


Played By: Jemma Redgrave
Tenure 2012-present
First appearance The Power of Three (regular)
Last appearanceInversion of the Zygons (regular)
Appearances6 stories

source TARDIS Wikia


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Kate is one UNIT’s top people and the daughter of Brigadier Alistair Gordon Lethbridge-Stewart, the military man who was such a good friend to The Doctor.

Kate Stewart is the Head of Scientific Research at UNIT, and as science now leads the organisation, that means she’s one of the people in charge. And so whenmillions of mysterious cubes began appearing on Earth she led the team tasked with monitoring and analysing them.

After her research proved bootless and sensors detected a spike in Artron energy, she investigated and met The Doctor for the first time. He had been an old friend of her father’s and happily, the bond she soon developed with the Time Lord proved to be a strong and valued one.

Kate is intelligent, quick-witted and has a dry sense of humour. She is prone to moments of doubt and anguish when the odds seem overwhelming, and at one point The Doctor gently raised her morale, reminding her that her father never gave in to despair.

She shares many of the Brigadier’s qualities including loyalty and faith in The Doctor, as well as a strong desire to serve humanity. But her approach differs markedly. Whereas his tactics were predicated by a military attitude, she learnt from the wisdom he ultimately passed to her. ‘Science leads, ‘ she recalled her dad telling her. ‘He said he’d learnt that from an old friend…’

Feditiona and Alistair had Kate three years into their marriage, which lasted eight years. As a child, Kate was never told of her father’s work at UNIT with aliens and was only aware that he was a military man. She would often pretend that he was off to have an amazing adventure when she really”knew” he was off to do boring militaryoperations. (Downtime)

at the time of the Wenley Moor Silurian incident, Kate was five. It was during this mission that Alistair realised that he was an inadequate father for her. The secretive nature of his work with UNIT prevented him from being consistently present in her life. His long absences from home caused Feditiona to leave him. Alistair guessed that she and Kate went off to at least initially live somewhere close to Chichester, the home of Kate’s maternal grandparents

Kate later married, had a second child, and became divorced. (Death in Heaven) She dropped the name “Lethbridge” when she joined UNIT so as to be judged on her own merits and not be perceived as being the beneficiary of nepotism. (The Power of Three)

Her father nevertheless quietly mentored her until his death. He instilled in her the position that”science leads”, something he learned from”an old friend” (i.e., The Doctor). Kate eventually rose to the post of Head of Scientific Research, and established UNIT as a military organisation led by its scientists. In this capacity, she summoned the Eleventh Doctor and Amy Pond via his psychic paper to the Tower of London to investigate the mystery of the Shakri cubes. Kate attempted to warn the governments of the world of the cubes when they started their countdown. (The Power of Three)

She ordered the airlifting of the TARDIS to London, to the agitatedition of the The Doctor. Kate summoned him there under the royal orders of Elizabeth I, giving him a sealed letter from the Queen and proving her credentials by showing him the impossible painting Gallifrey Falls No More within the National Gallery.

The letter decreed that The Doctor be made curator of the Under-Gallery, and that he be summoned should there be any disturbance there. Kate led The Doctor and Clara Oswald to the scene of the disturbance. There, she showed them more paintings, all landscapes with glass on the floor next to them. When The Doctor jumped through the fissure and met the Tenth Doctor and the War Doctor. Claraattempted to follow him before Kate restrained her.

As she left the room to request important UNIT files, Kate was accosted by a Zygon who had escaped through one of the paintings and then took her image and pretended to be the real Kate to Clara Oswald. Osgood saved her from the Zygon nest. Kate, along with McGillop and Osgood, confronted their Zygon doppelgängers in the Black Archive. Kate ordered the countdown to detonate the Archive which would not only have prevented the Zygons from having control of the many weapons stored there, but would also destroy London in the process. The Zygon used Kate’s voice to stop the detonation, but Kate countermanded the order.

Kate and her Zygon counterpart bickered over the detonation, before the Eleventh and Tenth Doctors triggered the memory modifiers to confuse everybody in the room as to whether they were a Zygon or a human. The two Kates stopped the countdown, and negotiated a peace treaty. (The Day of the Doctor)

UNIT had in its possession a picture of Kate with River Song. (The Day of the Doctor)

When the Cybermen rise, Kate arrives with Osgood and UNIT and takes Missy and The Doctor into custody. She reveals to the Twelfth Doctor that he is now President of Earth and works with him to battle the Cybermen. When the Cybermen attack the plane Boat One, Kate gets blown out by Missy, apparently to her death, but Clara and the Twelfth Doctor find her alive in a cemetery later, saved by a rogue Cyberman that kills Missy. The Doctor realises from what Kate is muttering about her father that the Cyberman that saved her is the Brigadier who’s love for her allowed him to retain his emotions. (Death in Heaven)

When Missy returned and froze all the planes on Earth, Clara came to UNIT and Kate helped her contact Missy. (The Magician’s Apprentice)

Kate and UNIT went to investigate a Zygon invasion that broke out after a rogue gang of them decided a peace treaty with humans was unacceptable. She was determined to bomb the rebel Zygon settlement, but The Doctor convinced her that this will only make the situation worse – threatening to radicalise every peaceful Zygon on the planet.

Kate folowed a lead to Truth or Consequences in New Mexico to try and find the route of the uprising. Here she encountered the one remaining inhabitant of the town, police sheriff Norlander, who explained how the trouble started – the accidental revelation of a young Zygon in true form, caused human panic, mayhem, distrust and violence. As the full horror of what happened in the town dawned on Kate, so does the fact that Norlander was actually a rebel Zygon agent. Kate is then attacked and apparently killed, with the Zygon taking her form. (The Zygon Invasion)

She was then attacked but managed to kill the Zygon, before taking its place to fool the High Command. Kate was present in the Black Archive when the Twelfth Doctor forced her to become an ambassador for the human race in an attempt to negotiate a new peace treaty alongside the Zygon High Command leader Bonnie in which a standoff occurred involving the Osgood Box. However, her memories of the Box were soon erased. (The Zygon Inversion)

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