Ping Cho in Marco Polo
Cameca in the Aztecs
Fariah in Enemy of the World
Chin Lee in Mind of Evil
Zilda in Robots of Death
Villagra in Four to Doomsday
Osborn in Resurrection of the Daleks
Matrona in Trial of a Time Lord
Shou Yuing and Bambera in Battlefield

It's fair comment to note that a large number of stories don't
have any women at all in, except for the companion.