A is for... Adeola

A member of Torchwood One, based at the Torchwood Tower in London's Docklands. She and her colleagues operated the systems which created the "ghost shifts", when thousands of shadowy figures would appear all over the planet. Torchwood was tapping into an energy source which had been discovered several hundred feet above London, and the Tower had been built to reach and enclose it. Adeola - surname Oshodi - decided to sneak off with her colleague Gareth for a romantic encounter in a part of the building that was closed for renovations. They were captured by Cybermen scouts and converted into their slaves. Both lured another colleague, Matt, to the same fate. Together, working under Cyber-control, they opened the rift between parallel universes to allow the Cybermen to travel across the Void from the Earth, where Cybus Industries had created them, and into ours. Adeola was killed when the Doctor removed the implant in her brain, though she was as good as dead anyway. It was too late to stop the Cybermen invading the Earth en masse.
The Doctor later met her cousin, Martha Jones, who looked just like her. She would become one of his travelling companions. Subconsciously, he may have felt some guilt about not being able to save Adeola.

Played by Freema Agyeman. Appearances: Army of Ghosts (2006).

• Freema got the Martha Jones role as the production team had been impressed with her in this relatively minor role. Making them related got round the fact that Martha was identical to her, and first appeared so soon after this story.
• Whilst two of the Doctors have been cast after first appearing in guest roles, there will be one further companion cast after appearing in an earlier story - Karen Gillan (Amy Pond) having appeared in the same story that featured Peter Capaldi in his other role (in The Fires of Pompeii). Ian Marter (Harry Sullivan) had also featured in another role not long before becoming a companion (as Lt. Andrews in Carnival of Monsters). John Leeson (the voice of K9) actually got to play another role in the middle of his stint as companion, as K9 did not feature in The Power of Kroll.