•
The Doctor has been UNIT's principal scientific advisor since their
third incarnation was exiled to Earth (having previously collaborated with UNIT during their
second incarnation). The Doctor departed from UNIT's full-time employment during their
fourth incarnation, leaving a space-time telegraph (and, later, the TARDIS's telephone number) with which they could be summoned in emergencies. They retain their credentials, still bearing their third incarnation's portrait; and, initially, UNIT personnel
Surgeon-Lieutenant Harry Sullivan and
Sarah Jane Smith as their
companions. Despite the looseness of their UNIT affiliation and their frequent disagreements with the organization, The Doctor continues to consider UNIT's scientific advisor to be their job, even into their
thirteenth, fourteenth and fifteenth incarnations. In several instances, the Doctor is often valued as being the ultimate authority, often being made President of Earth. •
Brigadier Alistair Gordon Lethbridge-Stewart (later Sir Alistair Gordon Lethbridge-Stewart) is a founder of UNIT and the original commander of its British contingent. During the Third Doctor's exile on Earth, he hires the Doctor as his scientific advisor. He was the father of Kate Lethbridge-Stewart, another UNIT commander. • Sergeant Benton first appears as Corporal Benton in
The Invasion and becomes a regular fixture of UNIT stories from
The Ambassadors of Death until
The Android Invasion. In his final three appearances, during the Fourth Doctor era, he has been promoted to
regimental sergeant major. •
Liz Shaw, originally drafted from the
University of Cambridge as UNIT's scientific advisor, first appears in
Spearhead from Space and accepts the position of the Third Doctor's assistant when he takes the job of scientific advisor. •
Jo Grant is a civilian employee of UNIT who was assigned as assistant to the Third Doctor, replacing Liz Shaw. The character appears from the serial
Terror of the Autons in 1971 until
The Green Death in 1973. According to the novelisation of
Terror of the Autons, she holds the rank of Corporal. • Captain Mike Yates also makes his first appearance in
Terror of the Autons and appears regularly throughout the Third Doctor era. He is an officer who mainly serves as Brigadier Lethbridge-Stewart's adjutant. •
Sarah Jane Smith is an
investigative journalist who becomes a UNIT associate by way of her companion relationship with the Third, Fourth,
Tenth and
Eleventh Doctors. Sarah Jane maintains contact with, and receives support from, senior UNIT personnel throughout her lifetime. •
Harry Sullivan, a Surgeon-Lieutenant in the Royal Navy, is a medical officer in UNIT at the time of the Doctor's third regeneration and becomes his companion for several adventures. • Petronella Osgood, played by
Ingrid Oliver, is a UNIT scientist and assistant to Kate Stewart in "
The Day of the Doctor" (2013). She wears a long, knitted scarf of many colours, reminiscent of the
Fourth Doctor's scarf, and suffers from a respiratory ailment for which she uses an inhaler when over-excited. In "The Day of the Doctor", she comes to be impersonated by a Zygon, and the two get along rather well. Following a peace treaty between humans and Zygons, which resulted in 20 million Zygons settling on earth disguised as humans, the Zygon duplicate remains in the form of Osgood, with neither version of Osgood revealing to others which is which. One version of Osgood works with Kate Stewart and the
Twelfth Doctor, in the episode "
Death in Heaven" (2014), wearing a
bow tie reminiscent of the
Eleventh Doctor and
Converse reminiscent of the
Tenth Doctor. She is shown to be eager to please the Doctor and admires him. The Doctor hints that he might consider making her a companion, but she is disintegrated by
Missy. Osgood displayed a great deal of self-control as she near-calmly tried persuading Missy to spare her with logical explanations. In "
The Zygon Invasion" (2015), the surviving Osgood is kidnapped by a splinter group of Zygons led by Bonnie, who seeks war with the humans. After being rescued by the Doctor, she travels with him to UNIT Black Archive in an attempt to keep the peace while refusing to tell him whether she is human or Zygon. In "
The Zygon Inversion", the Doctor, after successfully convincing Bonnie to live peacefully with humanity, offers Osgood a trip in the TARDIS. Osgood refuses, revealing Bonnie has become her new duplicate. •
Martha Jones, codename "Greyhound 6", becomes a medical doctor after her adventures with the Doctor, and subsequently a Medical Officer for UNIT. She contacts the Doctor so he could help UNIT in the episode "
The Sontaran Stratagem" (2008). She becomes trusted enough in UNIT to be given the Osterhagen Key, part of a mechanism for a program to destroy Earth. •
Kate Lethbridge-Stewart, also known as Kate Stewart, is the Commander in Chief of UNIT; formerly the Chief Scientific Officer and
de facto leader of UNIT's UK contingent in the 2010s and 2020s. She first appears in "
The Power of Three" (2012), introduced by
Chris Chibnall, before returning in the fiftieth anniversary special "
The Day of the Doctor" (2013) and subsequently recurring during the
Twelfth,
Thirteenth,
Fourteenth and
Fifteenth Doctor's eras. Kate is the daughter of Brigadier Lethbridge-Stewart. The character was created for the unofficial spin-off videos
Downtime (1995) and
Dæmos Rising (2004), in which she was played by
Beverley Cressman. She is depicted as a single mother to Gordon Lethbridge-Stewart, who to date has not been referred to in
Doctor Who, although Kate has referred to herself as a divorcee and "mother-of-two" (her second child being a daughter) in the programme. •
Tegan Jovanka is a former airhostess and former companion to the Fourth and
Fifth Doctors, she was hired to work as a freelancer for UNIT and employee by Kate Stewart before
The Power of the Doctor. She met the
Thirteenth and assisted her by blowing up the Cybermen and the new UNIT base and saw a hologram of an aged Fifth Doctor. •
Ace, who was a former companion to the
Seventh, was a 16-year-old when she first met the Doctor. She was hired to work as a freelancer for UNIT and employed by Kate Stewart before "
The Power of the Doctor". She met the
Thirteenth and assisted her by destroying the Daleks plan with her baseball bat and using her Nitro-9 with the assist of
Graham O'Brien and saw a hologram of an aged Seventh Doctor. • Shirley Anne Bingham is the 56th and current scientific adviser to UNIT who made her first appearance in
The Star Beast where she was in charge of investigating the seemingly crashed ship of
the Meep. She also assisted UNIT and the
Fourteenth Doctor in investigating the eponymous Giggle in
the Giggle, as well as being present in
Lucky Day and
The Reality War. She reappears in
The War Between the Land and the Sea, still as scientific adviser. •
Melanie Bush, a computer programmer and former companion to the
Sixth and
Seventh Doctors, she was hired to work as a computer scientist for UNIT by Kate Stewart sometime after 2022's
The Power of the Doctor. She was present for the
Fourteenth and
Fifteenth Doctors' battle against the Toymaker at UNIT Tower in 2023. She also fought against Sutekh in
Empire of Death, against Conrad in
Lucky Day and against Omega in
The Reality War. • Colonel Christofer Ibrahim is a UNIT field officer who answers directly to Kate Stewart and follows her without question. He made his debut in The Giggle, bringing the Doctor and Donna to his boss, and was present for the Toymaker's defeat. He later reappears in
The Legend of Ruby Sunday,
Empire of Death,
Lucky Day and
The Reality War; these episodes have a subplot where he is heavily implied to be in love with Kate. They are in a relationship during
The War Between the Land and the Sea, but he dies protecting Kate from an assassin in the story. • Donna Noble is recruited by Kate at the end of
The Giggle, in an unspecified capacity. • Rose Noble is shown working for UNIT in
The Legend of Ruby Sunday /
Empire of Death, in an unspecified capacity. She is later shown leading the UNIT resurgence against Conrad in
The Reality War. • Morris Gibbons is a thirteen-year-old boy genius and scientific advisor who appears in the series 14 two-part finale "
The Legend of Ruby Sunday" / "
Empire of Death". He is later mentioned in
The War Between the Land and the Sea. • Susan Triad is a woman who has been stalking the Fifteenth Doctor and Ruby during their travels. After Sutekh brings her to life in
Empire of Death, she is recruited by Kate to her personal staff, in an unspecified capacity. She returns in
The Reality War. • Ruby Sunday is revealed to have been recruited to UNIT after she and the Doctor parted ways. She is shown on Kate's personal staff alongside Shirley and Ibrahim from
Lucky Day onwards, though her exact role has never been revealed. • Barclay Pierre-Dupont was a Grade 10 clerk for UNIT who appeared as the main character in
The War Between the Land and the Sea. As a clerk, Barclay was responsible for handling transport such as taxis and finding cheaper lorries. In a strange twist of fate, Dupont was brought on board to a covert mission in Dragonera, replacing Roger Trevithick for whom he had once covered for in 2020. After showing respect to a fallen
Sea Devil, Barclay was named as the second human ambassador in peace talks between mankind and Homo Aqua, replacing the dismissed Sir Jonathan Hynes. • Sergeant Hana Chakri is a UNIT non-commissioned officer appearing in
The War Between the Land and the Sea, with responsibility for protecting Barclay. • Corporal Jane Hart is a UNIT soldier appearing in
The War Between the Land and the Sea. • Steve Chesney is a computer expert appearing in
The War Between the Land and the Sea.
Other media Originating in audio • Colonel Vikram Shindi is a field officer in the
UNIT: The New Series audio plays, an old-school, humourless soldier who follows Kate Stewart without question. • Captain Josh Carter is a company officer in
UNIT: The New Series, more of a man of action. • Lieutenant Sam Bishop is a company officer in
UNIT: The New Series, and serves as a troubleshooter. • Lieutenant Jimmy Tan is a company officer introduced later in
UNIT: The New Series.
Originating in TV but expanded in other media • Allison Williams is the assistant and scientific advisor to Professor Rachel Jensen when UNIT existed as the Incursion Countermeasures Group. She originated in
Remembrance of the Daleks but was fleshed out in the
Countermeasures audio series. ==Other appearances==