K is for... Kingdom, Sara

Sara Kingdom was a particularly ruthless member of the Space Special Security Service in the year 4000AD. She was tasked by her commander Karlton to hunt down a traitor named Bret Vyon, who was travelling with some unknown humans. Her orders were to shoot to kill. When Vyon arrived on Earth at a scientific research complex, Kingdom located him and shot him dead. When she tracked down the others - the Doctor and Steven Taylor - they were all three caught up in a matter-transmission experiment and beamed to the distant planet of Mira. 

Here, Sara learned that she had been lied to. Karlton's boss Mavic Chen, Guardian of the Solar System, was in league with the Daleks, and Vyon had been trying to warn Earth about this. She admitted to the Doctor and Steven that the dead agent had been her own brother.

Sara then joined the Doctor and Steven in their fight against Chen and the Daleks, who were plotting to destroy the Earth with a Time Destructor device. The Doctor had stolen the power source for this.

After seizing a Dalek spaceship they were able to reach the planet Kembel and the Doctor was reunited with his TARDIS. 

Sara's first destinations in history were a Liverpudlian police station at Christmas 1965, then a Hollywood film set of the silent era, where a director wanted her to make a movie with him. On the planet Tigus they were attacked by the Monk, an old foe of the Doctor and Steven. He pursued them to ancient Egypt, where Sara was captured by Chen and the Daleks. After escaping, they made their way to Kembel once more, where the Doctor operated the Time Destructor.

When its effects began to overpower him, Sara left the TARDIS to help him. He survived, but unfortunately she was aged to death.

Played by: Jean Marsh. Appearances: The Daleks' Master Plan (1965/66).

• The aged Sara was played by May Warden.
• This was the second of three appearances by Marsh in the series. Also for director Douglas Camfield she had played Joanna, sister to King Richard in The Crusade. In 1989 she was reunited with Nicholas Courtney (who had played Bret Vyon) in Battlefield, in which she played Morgaine.
• Although she only features within a single story, Sara has always been considered an official Doctor Who companion.
• The character was very much inspired by Diana Rigg's Mrs Peel in The Avengers. Despite being killed off, Terry Nation planned to resurrect the character for his proposed Dalek TV series, along with another brother. She features in stories and comic strips in the 1960's Dalek books.