Thomas Milligan

Thomas Milligan was a doctor who worked for the NHS in 2008. When the Master brought the Toclafane to Earth he became a fugitive. In 2009 he met Martha Jones when she returned to England and took her to see Professor Alison Docherty. When the Master tracked them down, he killed Tom with his laser screwdriver.

When the Master's Paradox Machine was destroyed reversing time back to 2008, Martha phoned doctor Thomas Milligan, and then hung up, knowing he was alive. (DW: Last of the Time Lords)

Behind the Scenes
Fans of the show speculated that he would be Martha's boyfriend in the 2008 series. This appears so but he will be mentioned not seen.