Chantal Osterberg was a scientist from “the Great Retrenchment” era.
At a young age, Chantal had been given an intelligence update, giving her an advantage over all other humans in 438,533. Returning to the point of humans being like sheep, a group of humans followed her to the year 26,185 BC where she promised them peaceful lives and where they could observe the history of their species.
She had bred her own species, the Hy-Bractors. Her intention was to use them to wipe out the human race. Her plans were thwarted by the intervention of the Ninth Doctor, and Chantal, attempting to escape to her own time, was accidentally eradicated by a fault in the time machine. (Only Human)