Martha Jones

Martha Jones is a female Human who worked as a medical student at the Royal Hope Hospital in London.

The twenty-three-year-old Martha was working at the hospital when she encountered the Doctor, and later joined him as his companion on his adventures. The Doctor insisted, however, that he had not brought Martha aboard the TARDIS as a replacement for his previous companion, Rose Tyler. (DW: Smith and Jones)

Family
Martha's mother was called Francine and her father was called Clive. She had an older sister, Letitia "Tish" Jones and a younger brother, Leo, who lived with his girlfriend and had a child. On the day that Martha first met the Doctor, her family had a row at her brother Leo's 21st birthday due to Clive insisting on bringing his young girlfriend Annalise, much to his estranged wife's disgust. The Jones parents eventually reconciled, after a year spent in captivity on the Master's fortress, the Valiant. (DW: Last of the Time Lords)

Martha's cousin, Adeola Oshodi, used to work for Torchwood 1 - she was killed when the Doctor overloaded the cyberman implant in her brain with his sonic screwdriver. (DW: Doomsday)

Alongside the Doctor
Martha Jones first met the Doctor in the street on the way to work; she had been on the phone to several members of her family when she bumped into him. He took off his tie, saying "Like so! You see?" before getting on his way. She looked momentarily confused before making her way to her work: she was a medical student at the Royal Hope Hospital in London. As she entered the building, she saw two men appearing like motorcycle couriers, and, soon after, whilst taking her jacket from her locker, she received a strong burst of static electricity.

Then, Martha was one of those present to review the Doctor's case. She examined him using a stethoscope and was shocked to discover that he has two hearts, although she didn't say anything to anyone else about it.

She helped him defeat the Plasmavore "Florence" when the hospital was transported to the Moon by the Judoon, and later joined him on his travels. Her first meeting tuned out to be a way for him to prove that he could use his TARDIS to travel through time as well as space. (DW: Smith and Jones)

Originally she was frightened of the effects that may occur from traveling through time, although the Doctor's apparent confusion over the matter later convinced her that it was not easy to change history. (DW: The Shakespeare Code)

After returning home in The Lazurus Experiment, the Doctor allowed her to stay on board the TARDIS. He gave her a mobile phone upgrade and a TARDIS key in the episode 42.

Time away from the Doctor
Martha spent a year travelling the Earth speaking of the Doctor whilst the Master ruled over them with the Toclafane. As a result of the destruction of the Master's Paradox Machine, only Martha and her family remembered that year spent with the Master. She decided she wanted to go and complete her medical studies, but gave the Doctor her phone; saying that she might want to return to travelling with him in the future. (DW: Last of the Time Lords)