Dr. Martha Jones is a fictional character played by Freema Agyeman in the long-running British science fiction television series Doctor Who and its spin-off series, Torchwood. She is a companion of the Tenth Doctor in Doctor Who, replacing Rose Tyler in the primary companion role. She made her debut in Series 3's "Smith and Jones", broadcast in the UK on 31 March 2007.
Within the series' narrative, Martha begins as a medical student who becomes the Doctor's time travelling companion after an incident at the hospital where she works.
After well over a year of being his companion, Martha parts from the Doctor's company. This is mainly because throughout the series she realized she was falling in love with the Doctor, yet he did not feel the same way. After returning to life on Earth, becoming engaged to Thomas Milligan and finishing her medical degree, Martha finds a newfound level of independence when she is recruited into the paranormal military organisations UNIT, and briefly Torchwood. Having faced the end of the world single-handedly during her time with the Doctor, Martha is recognised for her skills both in the field and in medicine.