Resurrection of the Daleks
Osborn was a crewmember of the Prison Station on which Davros was held as a prisoner.
She was one of the few survivors of the first Dalek raid on the station. She tried to carry out her duty and execute Davros before he could be freed, but she was shot and killed by the Daleks’ mercenaries. (Resurrection of the Daleks)
BEHIND THE SCENES
In Eric Saward’s novelisation of the story, Osborn’s first name is given as Fabian. This was not derived from any information given in the televised version.