Susan is introduced in the first Doctor Who story, An Unearthly Child (1963), with the first episode focusing on her as an unusual teenager with an advanced knowledge of history and science. This catches the attention of her teachers at Coal Hill School, Ian Chesterton (William Russell) and Barbara Wright (Jacqueline Hill), who follow her home to a junkyard owned by an unseen proprietor named I. M. Foreman. It is implied within the story that Susan took the surname "Foreman" from this junkyard sign as an alias for use at the school, for when her chemistry Teacher made the assumption that her grandfather was "Doctor Foreman" the Doctor replied, "Doctor who? What's he talking about?", indicating that he was unfamiliar with the surname. It is revealed that she and her grandfather, the Doctor (William Hartnell), are exiles from their own people in "another time, another world" and have been travelling through space and time in a machine she named the TARDIS from the acronym "Time and Relative Dimension in Space". As Ian and Barbara have gained this knowledge, the Doctor whisks them away on the TARDIS against their will, and he cannot accurately fly the machine. Through the run of the series, it is learned the Doctor, aided by Susan, stole the TARDIS.
Susan continues to travel with the Doctor and her two teachers until the 1964 serial, The Dalek Invasion of Earth. During the events of that story, Susan falls in love with David Campbell (Peter Fraser), a young freedom fighter in the 22nd century. However, Susan feels that she has to stay with and take care of her grandfather. The Doctor, realising that Susan is now a grown woman and deserves a Future away from him, locks her out of the TARDIS and leaves after a tearful farewell. Ford reprised the role of Susan on television in the 20th anniversary special The Five Doctors (1983), but no mention of David, or what became of him, was made on screen. In the novelisation of the same story, they are still married. Ford also reprised her role for the 1993 charity special Dimensions in Time.
In addition, the spin-off film adaptations Dr. Who and the Daleks (1965) and Daleks – Invasion Earth: 2150 A.D. (1966) have a version of Susan, portrayed by Roberta Tovey and much younger than the television version. Rather than being her Teacher, Barbara is either her older sister or her cousin.
Susan's character has been expounded upon in spin-off media. In 1983, Doctor Who's then-script Editor Eric Saward wrote a short story dealing with the Doctor's departure from Gallifrey for the Radio Times Doctor Who 20th Anniversary Special. This story, "Birth of a Renegade", depicts Susan as a descendant of Time Lord founder Rassilon and the last surviving member of Gallifrey's royal family, unrelated to the Doctor. A later script Editor, Andrew Cartmel, had another explanation of Susan's origins. This account, part of the "Cartmel Masterplan", was not used in the programme, but was used as background for several of the Virgin New Adventures novels, most notably Lungbarrow by Marc Platt. In this version, Susan is the granddaughter of the mysterious Gallifreyan founder known as the Other, who may have been reincarnated as the Doctor. The Doctor had travelled back to the dawn of Time Lord civilisation and rescued Susan, who recognised him as her grandfather. The Doctor did not initially recognise her, but knew that this was somehow true.
In The Curse of Fenric (1989), the Seventh Doctor (Sylvester McCoy) states that he does not know if he has any family. In "The End of the World" (2005), the Ninth Doctor (Christopher Eccleston) states that his home world has been destroyed and that he is the last of the Time Lords. Although Susan is not mentioned by name, the Ninth Doctor says in "Father's Day" (2005) that his "whole family" died, and in "The Empty Child" (2005), Doctor Constantine (Richard Wilson) remarks he has been a father and grandfather, but now he is neither, and the Ninth Doctor replies, "I know the feeling." In "Fear Her" (2006), the Tenth Doctor (David Tennant) states nonchalantly, "I was a dad once," but does not elaborate on this revelation. In "The Doctor's Daughter" (2008), the Tenth Doctor further clarifies to Donna Noble (Catherine Tate) that he had been a father prior to the creation of his "daughter" Jenny (Georgia Moffett), who was created by a machine using the Doctor's DNA, and that he "[l]ost all that a long time ago, along with everything else." In "The Rings of Akhaten" (2013), the Eleventh Doctor (Matt Smith) mentions that he travelled with his granddaughter to the rings of the planet Akhaten. The 2013 episode "Journey to the Centre of the TARDIS" contains audio from the scene in An Unearthly Child where Susan explains how she named the TARDIS. A brief glimpse of Susan, played by an unidentified body double, is seen in the opening scene of "The Name of the Doctor", which depicts the Doctor and Susan leaving Gallifrey in a TARDIS.
Ford stated that little background information on Susan's character or history was provided to her by the production team, and so to inform her performance, she would often discuss and invent ideas about Susan with co-star william Hartnell. They established that the Doctor had "done something to annoy the other Time Lords" which caused his and Susan's exile. Ford also points out that suggestions that Susan was not the Doctor's natural granddaughter were only first put forward in the 1990s. However, in 2013, she revealed that the producers had initially insisted that Susan not refer to the Doctor as her grandfather in The Five Doctors special. Ford recalled, "They said, 'We don't really want people to perceive him as having had sex with someone, to father a child.' I just screamed with hysterical laughter and said, 'In that case, I'm not doing it.'" The script was changed to include mentions of the characters' relationship.
On 9 July 1994, BBC Radio 4 broadcast Whatever Happened to Susan Foreman?, a humorous investigation into Susan's background. Susan was portrayed by Jane Asher. In the 2013 BBC drama An Adventure in Space and Time, which told the story of the first three years of the show, Claudia Grant played Carole Ann Ford.
Susan also appears, played by Ford, in the Companion Chronicles audio drama series from Big Finish. Quinnis (2010) takes place before the television series, when the Doctor and Susan were traveling alone. In the Big Finish bonus release An Earthly Child (2010), Susan is reunited with the Doctor in his eighth incarnation (Paul McGann), and has a son named Alex (Jake McGann). She appears in the Eighth Doctor Adventures audio plays in Relative Dimensions (2010) and Lucie Miller / To the Death (2011). Ford also played an alternate version of Susan in Big Finish's Doctor Who Unbound audio plays Auld Mortality (2003) and A Storm of Angels (2005), in which Susan has become President of Gallifrey. In the 2003 Doctor Who Unbound play Exile, an alternative Doctor, whose latest regeneration was female (played by Arabella Weir), settles on Earth in 2003 using the identity and 1963 school records of Susan Foreman.
Susan was the first ever on-screen companion of the Doctor, though Actress Carole Ann Ford felt that their relationship was different from that of later characters who had been branded as "companions" because she was also the Doctor's granddaughter. The original outline for the series did not intend the pair to be related, but Writer Anthony Coburn created the family tie. According to founding Producer Verity Lambert, "Coburn felt there was something not quite proper about an old man travelling around the galaxy with a young girl for a companion." The unaired pilot gave a different and more specific background to Susan and the Doctor, with their dialogue explaining that they came from the "forty-ninth century". Ford recalled that she was told Susan would be "an Avengers-type girl – with all the kapow of that – plus she would have telepathic powers. She was going to be able to "fly the TARDIS" as well as her grandfather and have the most extraordinary wardrobe". However, none of this happened as the character was decided to become more of an "ordinary" teenager which would give younger viewers an identification figure.
