Raj Kahnu

 was the Second Rani's favourite experiment. Chowdras said that he was cleverer at one year old than a three year old. He became a prince and an inventor. He was the child of the Rani. He created a suit of armour so that he could walk anywhere. He placed Constance Clarke into one of his suits. The Sixth Doctor cured him of his insomnia. The Rani tried to kill him in order to escape the planet. He thought of the Rani as his mother, although she never acknowledged this. (AUDIO: Planet of the Rani)

Behind the scenes

 * In the extras to Planet of the Rani, Marc Platt cited influence for Kahnu from Indian mythology.