Brenna (The Invention of Death)

Brenna was an Ashtallahn scientist. She and Sharlan met Barbara Wright and Susan Foreman, who introduced them to concepts which they found fascinating. She was present when Barbara was healed from a mortal wound with Ashtallahn cells. While she didn't understand the concept, Brenna loved Sharlan in much the same was as Sharlan did her. When Ashtallahns started dying, she assisted the First Doctor in finding the cause.

The Doctor succeeded in creating a child using cells from both Brenna and Sharlan. When the child came at risk of being infected by the plague, Brenna managed to protect the child. She mourned Sharlan's death, in spite of the fact that the plague was started by her. (AUDIO: The Invention of Death)