Sabetha

Sabetha was a young woman sent by Arbitan, her father, to find the keys to the Conscience of Marinus, but instead became enslaved in the city of Morphoton. After being freed, she accompanied the Doctor and his companions in their search for the keys.

She and Altos were romantically involved, a fact which was exploited by the Voord, Yartek. (DW: The Keys of Marinus)