Markus Schriver was a human scientist who worked for the Ides Scientific Institute. He experimented with creating a psychic link between astronauts and their ships, with his experiments forming the basis of the creature that became the Eminence.
The Eighth Doctor compared him to Mikhail Kalashnikov. Liv Chenka thought he was mad and that he was on the verge of a mental breakdown. In a fit of madness, he sealed Liv and Sally Armstrong in two mental extraction chambers and set them to random, which ultimately killed Sally. Schriver then fled. (AUDIO: Masterplan)
The Dalek Time Controller tracked him to the Eye of Orion. The Time Controller observed his final experiments. He recognised Liv when she arrived with the Time Controller. Schriver transferred his consciousness into the gas he created, and thus became the Eminence itself. The Supreme Dalek dispelled Schriver while he was trying to choke the Doctor, after which he attempted to mentally combat the Time Controller when he tried to transfer his consciousness into Eminence gas also. (AUDIO: Eye of Darkness)