Sarah Jane SmithPortrayed by: Elisabeth Sladen
Travelled with: Third Doctor, Forth Doctor, Tenth Doctor
Series: Classic, School Reunion (Series 2 : Episode 3), The Stolen Earth (Series 4 : Episode 12)/Journey's End (Series 4 : Episode 13)
Sarah Jane Smith first appeared posing as her aunt, a virologist, in order to infiltrate the UNIT-controlled facility where scientists had been disappearing. There, she met Brigadier Lethbridge-Stewart and his unpaid scientific advisor, the Third Doctor. Suspicious of the Doctor's activities, Sarah Jane stowed away on his TARDIS, travelling back in time to the 13th century where the Doctor defeated the Sontaran Linx in The Time Warrior (Classic Series), before becoming a companion of the Doctor. Together, Sarah Jane and the Doctor travelled on many adventures both on Earth and off, getting to know the Brigadier, Sergeant Benton and Captain Mike Yates of UNIT. Her first encounter with Daleks was in Death to the Daleks (Classic Series) alongside the Third Doctor where they defeated them. Sarah Jane was present at the Third Doctor's regeneration following radiation poisoning on Metebelis III. Sarah Jane initially believed the Doctor to be dead until his regeneration into his Fourth incarnation in front of her eyes. Soon after this, Harry Sullivan joined Sarah Jane as part of the TARDIS crew, and they travelled to numerous planets following the Fourth Doctor losing interest in Earth, though the Fourth Doctor and Sarah Jane seemed to enjoy a closer relationship. As part of her travels, Sarah Jane was present on Skaro when the Fourth Doctor was asked by the Time Lords to prevent the creation of the Daleks and assisted him in his attempts.
After many trips with the Doctor, Sarah Jane had to be left on Earth following a summons for the Doctor to return to Gallifrey. Gallifreyan law at the time forbid humans from being brought to the planet, though this law was lifted in the future. The Doctor took Sarah Jane home to Earth, and though he intended to leave her near her home in South Croydon, he failed, leaving her in Aberdeen instead. He did tell her that he would return for Sarah Jane but he never did, later citing in his Tenth incarnation that he feared becoming too attached to any individual human, due to the differences in Time Lord and Human life expectancies. The Doctor did not forget Sarah Jane however, sending her K9 Mark III as a keepsake and as a companion to her shortly before Christmas in 1981. Shortly after, Sarah Jane was captured by the Time Lord Borusa using a Time Scoop and placed in the Death Zone on Gallifrey alongside the Third Doctor, though K9 did not accompany her, where she also met his First, Second and Fifth incarnations as well as companions Susan Foreman and Turlough in The Five Doctors (Classic Series).
Eventually, K9 broke down and Sarah Jane was unable to fix him herself, and was unable to get anyone else to fix him due to his advanced alien technology, so resided to keeping him, broken down in her flat. Later, at Christmas 2006, Sarah Jane bore witness to the attempted Sycorax invasion to which she suspected the Doctor had some involvement after they failed. Some months later in 2007, Sarah Jane launched an investigation into the goings-on at Deffry Vale High School as an investigative journalist once more. There she met the Tenth Doctor, who was also investigating, as well as companions Rose Tyler and Mickey Smith, who became a member of the TARDIS crew following recommendation by Sarah Jane. Sarah Jane experienced initial competition, jealousy and animosity between herself and Rose, though this quickly dissipated and the two bonded well. Sarah Jane assisted the Tenth Doctor in defeating the Krillitanes at Deffry Vale High School, during which her K9 was destroyed in an explosion. On departing, the Tenth Doctor offered Sarah Jane the chance to travel with him again, but she declined, happy to have a proper farewell with him instead. He didn't leave her empty handed however, leaving behind a K9 Mark IV which included a Sonic Lipstick and a watch to scan for alien life hidden in a compartment.
Sarah Jane later assisted the Tenth Doctor again in The Stolen Earth (Series 4 : Episode 12) and Journey's End (Series 4 : Episode 13) where he met her adoptive son, Luke. The Tenth Doctor entered Sarah Jane's life on occasions, assisting her and her gang out every now and then, as did the Eleventh Doctor, with Sarah Jane attending his staged funeral. At the end of the Tenth Doctor's life, he paid a visit to Sarah Jane, saving Luke's life after he was nearly run over by a car. Sarah Jane watched the Doctor and smiled with a knowing look as if she knew what was about to happen to him.
As the Doctor's companion, Sarah Jane was inquisitive, no doubt to her investigative journalistic nature, confident and possessed a sharp mind, along with a sharp tongue. She was also something of a feminist, becoming infuriated when the Third Doctor asked her to make coffee in The Time Warrior, and often sparring with fellow companion Harry Sullivan over his chauvinistic and unintentionally patronising attitude towards her. Though she never said that she was in love with the Doctor, she did on many occasions come close, and conversations between her and Rose Tyler in School Reunion (Series 2 : Episode 3) suggests that she did have strong personal feelings for the Time Lord. It was noted that Sarah Jane always preferred to be called "Sarah Jane" over "Sarah", though to date the Doctor is the only person who gets away with regularly calling her "Sarah" without objection.