The Mistress was a robotic computer whose screen projected an image of a Uvodni woman.
- You may be looking for the Adventures in a Pocket Universe character.
She was wired into a Uvodni warship, and was ordering Uvlavad Kudlak to kidnap human children to fight in the Ghost Wars.
Kudlak thought she was real, and only sending a hologram, but this was not the case. When the Uvodni Emperor sent a transmission declaring that the Uvodni had made peace with their foes, Mistress hid it from Kudlak, to make him think the war wasn't over. She wanted to continue the war, because peace did not "compute", and knowing that without war, she would have no purpose.
After Sarah Jane Smith revealed the Mistress' deception and who she really was, Kudlak destroyed the computer in his anger. (TV: Warriors of Kudlak)