The Rani

"These are human beings, Rani. Living creatures that have done you no harm."

- The Doctor "They're carnivores. What harm have the animals in the fields done them? The rabbits they snare, the sheep they nourish to slaughter? Do they worry about the lesser species when the sink their teeth into a lamb chop?"

- The Rani

The Rani is a renegade Time Lady, amoral scientist and planetary dictator featured as a main villain in two story arcs of the classic BBC science fiction series Doctor Who, facing off against the Doctor in his sixth and seventh incarnations. She is a genius-level biochemist and inventor who rejected the Gallifreyan policies of non-interference over other races and became an outcast from their society. She was played by actress Kate O'Mara in both appearances, being one of the few Time Lord characters who appeared in multiple arcs in the series but remained in the same incarnation (the others were Susan Foreman and the Monk). Besides the TV series, she has also appeared in the novels State of Change and Divided Loyalties, and in the audio story The Rani Reaps the Whirlwind.

Personality
She views alien civilizations as nothing but potential subjects for her scientific experiments, and has no qualms about slavery, subjugation and even mass murder.

Beginning
The Rani was formerly a student at the same Academy as the Doctor and the Master, but was exiled after an incident in which she bred giant rodents which ended up devouring the Lord President's cat as well as part of the President himself (triggering a regeneration). In the novel Divided Loyalties, it is established that she was known as Ushas back then and was a member of the student society known as the Deca, to which also belonged Theta Sigma (the Doctor), Koschei (the Master), Magnus (the War Chief), Mortimus (the Monk) and Drax, among others. In "The Mark of the Rani", it is clear that she initially considers both the Doctor and the Master as little more than reckless idiots, although she agrees to ally with the latter when convinced that the former was a common enemy. Although definitely amoral, the Rani isn't needlessly evil and doesn't approve of the Master's sadism and willingness to kill gratuitously (although her opposition to this may have more to do with her considering it infantile than morally wrong).

At some point, she became the supreme ruler of a planet known as Miasima Goria and conducted massive scale experiments on the population, attempting to genetically enhance them. The experiments were having unfortunate collateral effects over the subjects' ability to sleep, causing violent behavior. To seek a cure for this she went to Earth to kidnap human beings, since she had effectively isolated the sleep factor on that species. She removed the brain fluid that controlled sleep in humans and as a result her subjects were left with altered behavior, becoming literally restless, overly aggressive and chaotic. To hide her activities, the Rani purposely operated on already turbulent periods of Earth history (namely the Trojan War, the Dark Ages, the American War of Independence and the Luddites' actions in the Industrial Revolution) so that the collateral effects on her subjects would be less noticeable or taken as results of these political and ideological conflicts. To ensure collaboration from selected individuals she also developed a genetically altered grub-like parasite which allowed her complete control over the minds of those who ingested it. Among her other inventions is a device that instantly converts animal into vegetable matter (in other words: turns people into trees). She also keeps numerous dinosaur embryos in her TARDIS, taken from a visit to the Cretaceous period, although the purpose of these is not revealed.

Teaming up with the Master
She met with the Master on Killingworth, Earth, during the Industrial Revolution, as he was hoping to mess up with history by interfering with the activities of the most influential minds of the time. He informed the Rani that the Doctor was around, investigating time distortions caused by manipulating Earth history and the strange behavior of some local men who had gone berserk; and that he would surely pose a threat to both of their schemes. She reluctantly agreed on an alliance, although disapproving of the Master's obsessive enmity with the Doctor. As it turns out, the Doctor manages to restrain them both and, while they end up escaping on the Rani's TARDIS, it is revealed that the Doctor had sabotaged the navigational controls, causing them to spin into a "time spillage", being dragged to the outer reaches of the universe. To make matters worse, the time spillage causes time anomalies inside the Rani's TARDIS, resulting in one of the Tyrannosaurus embryos rapidly growing to adult size and threatening them.

She next appeared in "Time and the Rani", in which it's revealed that she survived the Tyrannosaurus incident and allied herself with a race of bloodsucking bat-like aliens known as Tetraps, which she employed as minions. She landed her TARDIS on the peaceful planet of Lakertya, home to a scaly humanoid species. In this story the Rani is revealed as far more ambitious and even more technologically ingenious than the previous one. Having previously abducted a collection of geniuses from over the galaxy (including Albert Einstein), she chose Lakertya due to its proximity to an asteroid made of something called "strange matter". By hooking up the abductees' brains to power a super computer, the Rani hoped to find the means to synthesize a lightweight substance called loyhargil, which could be used to annihilate strange matter. If successful, she planned to fuel a rocket with this and aim it at the asteroid during its closest passage, which would cause a chain reaction in the upper atmosphere that would eventually convert the entire planet into a time manipulator device (destroying all life on the planet in the process) which the Rani hoped could be used to rewrite history on several worlds throughout the galaxy. She first planned to use it on Earth to prevent the extinction of the Mesozoic dinosaurs, following her previous remark that those creatures had never reached their full evolutionary potential.

Once on Lakertya she decided that her old colleague and enemy, the Doctor, would be a nice addition to her collection of high intellects, and somehow managed to locate and take down his TARDIS. The crash caused the Doctor to regenerate into his seventh form, with the resulting post-regeneration amnesia being useful for the Rani, who disguised herself as the Doctor's companion Mel and managed to convince the confused Doctor of her fake identity for some time. The Doctor would later foil her plans once again, redirecting the missile and saving the Lakertyans from eradication. Having learned that the Rani was planning to allow themselves to be destroyed as well, the Tetraps rebelled against her, making her a prisoner in her own TARDIS and forcing her to go back to their homeworld where she would help them with a more noble cause: seeking solutions for the massive food shortage that threatened their population.

Final Fate and Time War
Following the Doctor's claims of being the last of his race in the new series, it can be implied that the Rani died at some point before or during the Last Great Time War against the Daleks, although that remains unconfirmed.

Trivia

 * Russell T Davies said that, if the Rani was brought back, she would probably have been portrayed by Ruthie Henshall. However as he's stepped down from his possition as Script Editor, its unlikely this will ever occur.