Kephra
The Kephra were a species who conquered by subterfuge instead of violence. They would slowly take over a planet, making the inhabitants think more like themselves. The Kephras were known by different names by different species.
The Kephras came to Tarron after the colonists from Earth had settled the planet. Seeing the problems affecting the planet, they formed the Azmec Corporation and took over, claiming they had been given control by the founders. Centuries later, when the humans had developed the technology to see through the subterfuge, they kidnapped Akha Vorass from the past and used him to kill the top scientists. With the help of the First Doctor and Dodo, the humans found out the truth and banished the Kephra from the planet. (VD: Tarnished Image)
