The Orion androids, known derisively as the Android Hordes, were a group of human-built androids who revolted against serving humanity and created a society for themselves in Orion. They fought the 26th century Orion War against the Earth Empire. (AUDIO: Sword of Orion, Scorpius, PROSE: Legacy, et al)
History
By the early 26th century, androids were commonplace in Earth Empire society, but were viewed as an under-class. The androids finally became fed up with the situation and moved en masse to the relatively unused Orion System. They set up their own government, with the stipulation that humans living in the system could stay if they accepted android rule. The Earth Empire considered this a violation of sentient rights, and attacked, starting the Orion War. The Earth Military tried to use Cybermen against the androids, which eventually resulted in the Cyber-Wars. (AUDIO: Sword of Orion)
Some humans sympathised with their cause. (AUDIO: Scorpius)
Keri, an investigative journalist, lived with Orion android warriors on Bala for a story for GFTV-3. (PROSE: Legacy)
The Orion androids still existed circa the 40th century. During her time with GFTV-3, Keri once lived with Orion android warriors on Bala. (PROSE: Legacy)
Nearly 2000 years after the Orion War, the Seventh Doctor encountered two reprogrammed Orion androids, Sara and Temeter, on Reclaim Platform Juliet-November-Kilo. (AUDIO: Keepsake)
Behind the scenes
The Orion androids originate from the Audio Visuals story Sword of Orion, which was remade into the Big Finish story of the same name.