Ferdinand du Vindice
Ferdinand du Vindice was a lord in the Morestran Empire.
When his younger sister Castiza spurned the advances of a cardinal of the Morestran Orthodox Church, she was framed for involvement in the theft of forbidden technology. She was forced to become a nun at a secret nunnery of the Order of Perpetual Enlightenment.
Ferdinand searched for her for four years. When he found her, she discovered her tongue had been cut out. He killed the cardinal responsible, but instead of being punished, he was conscripted by the new Special Investigations Service whose purpose was to discredit the Church.
He helped the Fifth Doctor find out the truth about the Energy Tower and sacrificed himself to save the Doctor and Nyssa from a horde of anti-men. (PROSE: Zeta Major)