Xanxia

Xanxia was the queen of Zanak. She was practically frozen at extreme age in time dams and watched over by the Captain.

Biography
At some point, Xanxia created a hologram of herself, with which she could pretend to be the Captain's nurse. She persuaded him to jump Zanak continually through space to plunder planets for rare minerals to feed the time dams.

Xanxia hoped to create a permanently youthful, viable body by preserving her true form in its last few seconds of life. The Fourth Doctor dismissed this as foolish, stating that there wasn't enough energy in the universe to keep the dams running forever. She would always be dependent on the last few seconds of life in her old body. Xanxia was defeated by the Doctor when Zanak was prevented from materialising around Earth. The distraction caused by this failure allowed the time dams and the mountain in which they were enclosed to finally be destroyed by the Mentiads. (TV: The Pirate Planet)