Sibor (Prisoners of Fate)

Sibor was a member of the government on Valderon. She was a judge and convicted criminals based on predictions using the Doctor's first TARDIS, a Type 50. From this. she charged Tegan Jovanka and Vislor Turlough of murder. She wanted to blackmail the Earth Empire with the cure for Richter's Syndrome. She found and tortured the Type 50 to get it to do her bidding. When she discovered the Fifth Doctor planning to return it to Gallifrey, she tried to reactivate it, killing herself in the process. The Type 50 then used her corpse to communicate with the Doctor. (AUDIO: Prisoners of Fate)