The Eminence was a gaseous entity and psychic force that travelled across the universe in teleportation caskets. It could control the minds of any being it came into contact with, as long as it inhaled the breath of forever, turning them into its infinite warriors. (AUDIO: The Seeds of War)
The Doctor first fought the Eminence in his fourth incarnation on Delafoss. The Eminence created a ship called the Infinite, which it planned to use to end its war against the Earth Alliance. It breathed its breath of forever into the Doctor, and left him in command of the Infinite. The Doctor used his telepathy to trick the Eminence, and destroyed the Infinite. The Eminence subsequently lost its hold over Delafoss. (AUDIO: Destroy the Infinite)
The Eminence spent many years at war with humanity. The planet Kalsos was on the front lines of the war.
A thousand Eminence teleportation caskets travelled to the Nixyce system with the intention of taking over humanity. Seeing that in a possible future the Eminence would end up as the only life for in the universe, the Time Lords sent the Master to steal one of the caskets. The Master and took it back in time to 1970s London and experimented on the Eminence. When the Eighth Doctor came to investigate, he opened up the link to the Eminence in his mind and allowed the Eminence to pilot the Master's TARDIS. The Master managed to expel the Eminence into the Time Vortex. (AUDIO: Eyes of the Master)
The Daleks detected the presence of an Eminence fleet at the edge of the Nixyce system. (AUDIO: The Traitor) The Eighth Doctor teamed up with the Daleks against the Eminence. The Dalek time controller used the weapon they had built on Nixyce VII to destroy the Eminence fleet. (AUDIO: Time's Horizon, Eyes of the Master)
Around a thousand years later, the Eminence resided at the edge of the universe. The Orpheus travelled to the Eminence's location and attempted to siphon its power in order to get home. The Eminence began to possess the crew of the ship. (AUDIO: Time's Horizon)