Sara Kingdom

Sara Kingdom was a Space Security Service (SSS) agent who turned against Mavic Chen, the traitorous Guardian of the Solar System. With the help of the First Doctor and Steven Taylor, she defeated Chen and his secret allies, the Daleks. The price of victory was, however, her own life. (TV: The Daleks' Master Plan)

Early life and career
Sara had two brothers, both fellow SSS agents — David Kingdom and Bret Vyon, the latter of which the Doctor also encountered on Kembel. (TV: The Daleks' Master Plan, AUDIO: The Destroyers)

She was a high-ranking and original member of the SSS. At the foundation of the Space Security Service, she was chosen by Colonel Marc Foster and the artificial intelligence Compuvac as an agent in charge of the organisation's field operations. As a woman, she was chosen for the first mission of the agency and she was sent to Barzilla to divert the plans of the Golden Dalek from Earth to that planet, by spreading the news of its gold mines among the Dalek spies. The trap worked, the Dalek forces were annihilated by their enemy alliance and she was praised for the success of the mission. (PROSE: The Outlaw Planet)

Sara, with fellow SSS agents Jason Corey, the humanoid robot Mark Seven and her brother David Kingdom, encountered the Daleks in a brief confrontation early in her career. David went missing at the end of the mission. (AUDIO: The Destroyers) Trained and efficient, Sara had the strength of ten men. She was sent to planet Vara to rescue the kidnapped Professor Lomberg and prevent him to be forced by the Daleks to give them a formula of a metal for a new outer casing which would have made them unstoppable. She leaked in the Dalek slave camps, found the Professor and helped him to give the Daleks a wrong formula. That led into blowing up the camp and foiling the Daleks' plans. (COMIC: Sara Kingdom: Space Security Agent)

She was charged to investigate the leaking of confidential information that the Daleks were using to attack Earth strategic bases. She discovered the new Dalek emperor was able to read the thoughts of Earth's defence scientists through radio waves. She made up a plan that employed those scientists as a bait for the Emperor, while human forces attacked and wiped out the Dalek fleet of the Emperor. (COMIC: The Brain Tappers)

Mark Seven had written a file about the mission where David Kingdom got lost, which Mavic Chen consulted when he and Bret Vyon unexpectedly met Sara in 3999; she was supposed to be stationed on Venus at the time. Sara received a surprise promotion from Chen at this time. (AUDIO: The Guardian of the Solar System)

Adventures with the Doctor
On Earth the following year, she was briefed by Chen and was told her brother was a traitor. In an experimental testing facility, she found the Doctor, Steven Taylor, and her brother, the last of whom she shot to death. Sara would have done the same to the Doctor and Steven, but all three were accidentally transferred from Earth to Mira by cellular transportation. There she learnt, to her horror and grief, that her unquestioning obedience had not only led her to unjustly kill her brother but had prevented Vyon from warning Earth of the Dalek plot. She joined the Doctor in his fight.

With Steven and the Doctor, Sara took a short, stress-free trip to (in Sara's terms) long-ago Earth. (TV: The Daleks' Master Plan, PROSE: The Little Drummer Boy) After spending Christmas Day on Earth, Sara and the others spent six months having other adventures before once more getting involved with the issue of the Daleks and Chen. (PROSE: The Mutation of Time) They visited 3999, where Sara met Vyon and had an audience with Chen, which finally explained why she had been promoted in that year. (AUDIO: The Guardian of the Solar System) After further travels in the Doctor's TARDIS, (AUDIO: The Anachronauts, An Ordinary Life, PROSE: The Little Drummer Boy) they came upon a house in Ely that granted wishes; after the adventure, a copy of her mind lived on inside it for thousands of years. (AUDIO: Home Truths) After that, they once more returned to the struggle against the Daleks on several worlds and time periods.

The Daleks turned against Mavic Chen (who intended to betray them) and killed him. The Doctor had returned to Kembel to activate the Time Destructor to finally stop them. The Doctor ordered his companions back to the TARDIS for their protection. However, Sara followed him, not knowing the nature of his plan but concerned it might fail. She was caught in the field of the Time Destructor and, being a human rather than a Time Lord, aged to death. As Steven and the Doctor watched helplessly, Sara died, her remains ageing to dust. (TV: The Daleks' Master Plan)

Undated events
A photograph existed in UNIT's Black Archive showing Kingdom standing next to UNIT Captain Mike Yates, who was primarily associated with the Third Doctor. (TV: The Day of the Doctor)

Legacy
The death of Sara, as well as their other allies Bret Vyon and Katarina, caused Steven to confront the Doctor about the violence that seemed to follow him. (TV: The Massacre of St Bartholomew's Eve)

In his seventh incarnation, on the ruined planet Adeki, the Doctor thought that he'd found Sara Kingdom among others of his companions alive again and desperate to leave in the TARDIS. He learned that one of a race of shape-shifting Gwanzulum had used his sentiment in order to manipulate him into helping it escape the dead world. (COMIC: Planet of the Dead)

Later, while in a Hell-like world composed of the Seventh Doctor's mind, Ace met an eerie, ghost-like recreation of Sara Kingdom among his companions who had died because of him. Ace didn't recognise her. (PROSE: Timewyrm: Revelation)

Reincarnation
The copy of Sara Kingdom's mind left behind in the house in Ely lived on into an age of Earth's history in which advanced technology had become almost non-existent. An academic named Robert befriended her, interested in hearing stories from her past. Eventually, Robert wished to take her place as the entity inhabiting the house, and the alternate Sara was given human form as an older woman. Robert drew the Doctor's TARDIS back to the house, and allowed Sara to choose whether to join with the Doctor (in a later incarnation) or to remain on Earth. (AUDIO: Home Truths, AUDIO: The Drowned World, AUDIO: The Guardian of the Solar System) This version of Sara later joined Steven, Ian Chesterton, Polly Wright, and Nyssa in being abducted by Borusa, utilising a Time Scoop, to an alternative version of the Death Zone on Gallifrey, where she met the Fifth Doctor and once again battled the Daleks as well as the Sontarans. (AUDIO: The Five Companions)

Personality
Sara was by turns aggressive, independent, and ruthless in her pursuit of what was right, a single-mindedness that blinded her to the larger implications of her orders. She used to be without mercy about any casualties among the Dalek slaves (COMIC:  Space Security Agent) or causing riots on other planets (PROSE: The Outlaw Planet) for the sake of her missions. Meeting the Doctor changed that, and she turned her formidable skill and intellect to the defeat of the Daleks. (TV: The Daleks' Master Plan)

Steven later commented that he and Sara fast became friends over the course of their travels and that their relationship might have developed further if Sara had survived. (AUDIO: The Anachronauts)

Behind the scenes

 * In two recent interviews about her involvement with the character, Marsh has firmly and consistently maintained that Sara was not actually a companion. (DOC: From Kingdom to Queen, AUDIO extra features: The Drowned World) Despite this, over time she has come to be regarded as one in official BBC listings, reference works, and most recently by her inclusion in The Companion Chronicles series. Novelist John Peel established Sara as having spent at least six months travelling with the Doctor in the continuity of the Target novelisations. Sara was not the last character whose status is controversial, and she was joined by numerous "one-off" companions featured in the 1996 TV movie and post-2005 specials.
 * The DVD documentary Girls! Girls! Girls! - The 1960s (included on the 2008 release of The Rescue/The Romans) indicates that the character of Sara Kingdom was inspired by the character of Catherine Gale on The Avengers (coincidentally, a series created by one of the originators of Doctor Who, Sydney Newman). Marsh's physical similarity to Diana Rigg has led some to erroneously state that the inspiration was another character, Emma Peel, but Rigg had not yet made her first appearance on the series when the serial was in production.
 * Terry Nation planned to feature Sara Kingdom in an American spin-off series. Had it gone into production, the series would have concentrated on an anti-Dalek task force. Some of the concepts which would have featured in the show appeared in The Dalek Outer Space Book (in which she was featured in a short story and two comic strips). Sara appeared in the pilot script written by Nation, entitled The Destroyers. When plans for the spin-off fell through, Nation adapted his ideas and characters for The Daleks' Master Plan.
 * Jean Marsh had earlier appeared in Doctor Who, playing King Richard's sister Joanna in The Crusade. She returned to the programme in the 1989 serial Battlefield, playing Morgaine, coincidentally alongside Nicholas Courtney as Brigadier Lethbridge-Stewart (Courtney had played Bret Vyon in The Daleks' Master Plan).
 * Despite the character's brief tenure, there have been some spin-off works including her. John Peel, who novelised The Daleks Master Plan for Target Books, intentionally introduced a gap of several months in his adaptation into which such stories could be inserted. Most recently, Jean Marsh has reprised the character for three instalments of Big Finish Productions' The Companion Chronicles audio drama line. These stories take place between instalments of The Daleks' Master Plan and reveal that Sara has survived as an apparition.