Sandra Mitchell

Adam's mum was the wife of Geoff and the mother of Adam Mitchell.

When Adam went to travel in the Doctor's TARDIS, she believed he was still working at Henry van Statten's museum.

When Adam had an implant in his head from 200,000 (which, at the click of fingers, would open a small circle on his head, exposing his brain) he tried to record Internet codes on her phone while she was out.

After Adam tried to upload the Internet, the Ninth Doctor abandoned Adam back at his house in 2012. Adam's mum returned, saying time flies "just like that", clicking her fingers, then watching in horror as her son's head opened up. (TV: The Long Game)

Adam's mum died of a brain embolism shortly after Adam was returned to the 21st century. Adam blamed her death on the Doctor, who had erased the information that he had gathered from the future that could have saved her, and began planning an elaborate plot to get revenge on him. (COMIC: Prisoners of Time)

Behind the scenes
The first name of Adam's mum is never given on-screen or in the credits, but is given as Sandra in Doctor Who: The Encyclopedia.