Jennifer Harrison

Dr Jennifer Harrison began working at the Morden Clinic circa 1983, vivisecting aliens for Annabel Morden. She was interrupted by UNIT before operating on the Helliax and later took blood samples from the Fifth Doctor. She was taken into UNIT custody and killed by an alien. (AUDIO: The Helliax Rift)

Behind the scenes
The script describes her as "(F, late 30s) Doctor experienced in alien life, having abandoned her profession. Ready to take risks for her career."