Kadiatu Lethbridge-Stewart is a fictional character from the Virgin New Adventures range of spin-offs based on the BBC science fiction television series Doctor Who. She is a descendant of Brigadier Lethbridge-Stewart.

A character called Kadiatu Lethbridge-Stewart appeared in Ben Aaronovitch's novelisation of Remembrance of the Daleks (but not in the original television serial). That was in fact Kadiatu's great-grandmother, who wrote The Zen Military — A History of UNIT, which, in the fictional world of Doctor Who, was published in 2006.

Kadiatu's first appearance was in Aarononvitch's New Adventure novel Transit. Her adopted father is Brigadier Yembe Lethbridge-Stewart, a commanding officer in the United Nations Third Tactical Response Brigade and the Zen Brigade during the Thousand Day war between Earth and the Ice Warriors. He is descended from Brigadier Lethbridge-Stewart and an African woman, Mariatu, whom the Brigadier had a relationship with whilst serving in Africa. Brigadier Yembe rescued Kadiatu from a research centre in Leipzig when she was three months old, acting on information received from a possible future Doctor. She had been genetically augmented with unknown technology, although some of her augmentations, such as her musculature, have similarities to Time Lord physiology. These augmentations have given her increased intelligence and rapid healing. She has also never had any form of illness or sickness.

Brigadier Alistair Gordon Lethbridge-Stewart, generally referred to simply as the Brigadier, is a fictional character in the British science fiction television series Doctor Who, created by writers Mervyn Haisman and Henry Lincoln and played by Nicholas Courtney. He is one of the founders of UNIT (United Nations Intelligence Taskforce, later Unified Intelligence Taskforce), an international organization that defends Earth from alien threats, and serves as commander of the British contingent. Presented at first as reluctant to accept the continuing aid of the Doctor, over time the Brigadier became one of the Doctor's greatest friends and his principal ally in defending the Earth. The Brigadier has received a DSO and a CBE.

As one of the series' most prominent recurring characters over its fifty-year history, the Brigadier appeared in 23 stories during the original run of Doctor Who, first appearing in the 1968 serial The Web of Fear opposite the Second Doctor (Patrick Troughton). The character made frequent appearances on the show following the introduction of the Third Doctor (Jon Pertwee) in 1970's Spearhead from Space. His final appearance in the program was in 1989's Battlefield opposite the Seventh Doctor (Sylvester McCoy). Nearly 20 years later, Courtney reprised the role in the spin-off programme The Sarah Jane Adventures in 2008, his last appearance prior to Courtney's death in 2011. That year, Doctor Who later paid tribute to Courtney by announcing the Brigadier had died with a line of dialogue in "The Wedding of River Song". Later still, a Cyberman avatar of the Brigadier also appears, and achieves some closure with the Twelfth Doctor (Peter Capaldi), in "Death in Heaven" (2014).