Kate Lethbridge-Stewart

Played by Jemma Redgrave

"Science leads, he always told me. Said he'd learned that from an old friend"

Kate Lethbridge-Stewart is the commander-in-chief of the Unified Intelligence Taskforce. She also happens to be the daughter of the late, esteemed Brigadier Alistair Gordon Lethbridge-Stewart, the long-time friend and colleague of the Doctor. Practical, disciplined and determined, she is a firm believer that science leads over a more traditional military response when the Earth is under attack. 

Kate ascended the ranks of UNIT as 'Kate Stewart', initially hiding her family name to avoid any favours. However, as she leads UNIT into an era of public recognition, she fully embraces her father's legacy as a crucial tenet of the organisation. Frequently hiring the Doctor's former companions and allies, Kate values the knowledge and experience that a time-traveller can bring to UNIT.

Character Bio

After the mysterious Shakri cubes arrive in the night, Kate uses psychic paper to summon the Eleventh Doctor, meeting the Time Lord for the first time. Recognising her as the Brigadier's daughter, the Doctor rekindles his allyship with UNIT, respecting the science-first approach of Kate's leadership.

If the situation arises, Kate won’t flinch from taking painful decisions. When a Zygon invasion reaches the secret UNIT base under the Tower of London, rather than allow the collection of alien weaponry to fall under the control of the Zygons, Kate threatens to self-destruct the entire Black Archive, destroying London in the process. Thankfully, the Doctor is able to prevent this from happening!

She regularly finds herself in the line of fire; when the presidential plane comes under attack from Cybermen in mid-air, Kate is sucked out. Fortunately her father, who had been converted into a Cyberman, is able to fly up into the sky and save her.

It is Kate's intelligence and strategic senses that made her recognise the infiltration and control of UNIT by a disguised Grand Serpent in 2017, managing to avoid an assassination attempt and going underground to lead the resistance against the Sontarans. It is in the heat of this invasion that she is finally able to meet the Thirteenth Doctor for the first time.

With UNIT's budget and reputation restored after the Grand Serpent's interference, Kate leads the organisation into a new era, that comes with a massive and technologically upgraded headquarters in the middle of London. It is at UNIT Tower where Kate leads the investigation into the global crisis known as 'the Giggle', an otherworldly phenomenon caused by the Toymaker to drive the population mad. When the Fourteenth Doctor and Donna Noble intervene, Kate is present to witness the Time Lord bi-generate; and when the two Doctors defeat the Toymaker together, Kate has his remains bound in salt and locked away deep in UNIT's Black Archive.

While helping the Fifteenth Doctor investigate both Susan Triad and the identity of Ruby Sunday's mother, Kate and her team are witness to the resurrection of Sutekh, the God of Death. Initially succumbing to his Dust of Death, Kate faces her defeat with bravery and hope that the Doctor would save them all - a hope that was thankfully not misplaced, as the Doctor and Ruby's defeat of Sutekh reversed his actions and restored the lives of Kate and all their other allies.

In 2025, Kate responds to a call from Ruby Sunday sharing her concerns about the Shreek, an escaped creature that had previously targeted her new boyfriend, Conrad Clark. Arriving on the scene with full backup, Kate is rattled to find that the Shreek incursion was a set-up by Conrad and his allies at Think Tank, an activist group set up to expose UNIT’s “lies”.  

While attempting to run damage control as Conrad’s story becomes national news, Kate is in the UNIT building when he infiltrates it, while streaming from a body cam. Determined to protect her father’s legacy, Kate arranges for the real Shreek, held in captivity in UNIT’s containment zone, to be released on Conrad. As he panics, Kate taunts Conrad over his lies until he confesses to making everything up – a move that Colonel Ibrahim later warns her may have been a costly gamble.  

In Conrad Clark’s Wish World, Kate is the no-nonsense tweed-clad manager of the Unified National Insurance Team. When the Doctor and Anita Benn restore real time to the reality, Kate resumes her duties as commander of UNIT – waging battle against the colossal Bone Beasts, as UNIT Tower becomes an active battle station!