Petra Williams (Inferno Earth)

A parallel version of Petra Williams known in the Inferno Earth as Dr. Petra Williams was the second leader of the Inferno Project which was "scientific labour camp" which was attempting to drill down to the Earth's core. She was loyal to her employers until the true danger was revealed at which she assisted The Doctor to get back to his own world.

She was last seen hugging Greg Sutton as the lava from the shaft poured onto the Earth's surface. (DW: Inferno)