Sara (Kingdom of Silver)

 was an android who landed on Tessak, Magus Riga placed her in prison. She was rescued by Temeter, and continued her mission to find out any advances of the Cybermen, for the android cause. (AUDIO: Kingdom of Silver)

She was later put on trial for her failure on Tessak and on board the Sunbow. Her sentence was to be reprogrammed as a service droid. In this state she met the Seventh Doctor again. (AUDIO: Keepsake)