Ganger
The Gangers- a shortened form of 'Doppelganger'- were a clone race created by humans, typically controlled by their templates via specially-designed harnesses, allowing humans to work in hostile environments without risk to themselves as the Gangers could be easily recreated and any damage they sustained would not be felt by the real human as the nerve endings automatically shut down. However, when a solar storm struck a factory using Gangers, the five active Gangers gained independent thought and motion, being implanted with the memories of their templates and becoming increasingly fixated on the possibility of making their own lives. (DW: The Rebel Flesh)
In their 'natural' form Gangers were composed of a viscous white substance. In this state they seemed to retain some sentience and could copy the DNA of an individual that came in contact with the substance to create a Ganger copy of them. When they solidifed, the looked practically identical to their templates, but the independent Gangers retained the colour and texture of their liquid form, allowing them to be distinguished from their templates.
