Phiadorans were a species that resembled beautiful, fit human women with slightly elfin ears.
The Phiadorans were rulers of a ruthless matriarchal dictatorship. They maintained control of their subjects through genetically modified pheromonal glands that subverted the will of humanoid males. They were eventually overthrown and exiled to what may have been their own park on the Moon, but their empire collapsed shortly after.
The Phiadorans were taken as hosts by the Vrall found on the Moon, with the Vrall apparently replacing a significant portion of the Phiadorans' skeletal structure to make room for themselves. With access to the Phiadorans' memories while destroying their free will, the Vrall intended to use their hosts' more pleasant appearance to trick others into aiding in their escape. The Phiadorians were eventually abandoned as hosts when the Vrall were taken to Earth by the British Imperial Spacefleet, with the Vrall being subsequently destroyed by the Fifth Doctor, Turlough, and Kamelion. (PROSE: Imperial Moon)