Elystrian robot

The robots built on Elystria were developed by Vayla to perform menial tasks for the Elystrians. However, the robots turned on Vayla and wiped out the majority of the Elystrians, driving the rest underground. The robots based themselves in the planet's stronghold and increased their numbers by building more of their kind.

The Fourth Doctor rescued Vayla from the stronghold and Adric used a co-ordination control he stole to deactivate the robots. (DWAN: Planet of Paradise)