Over the course of its many years on television, the long-running British science fiction television series Doctor Who has not only seen changes in the actors to play the Doctor, but in the supporting cast as well.
The Doctor is usually accompanied in his travels by one to three companions (sometimes called assistants). These characters provide a surrogate with whom the audience can identify, and further the story by asking questions and getting into trouble, (similar to Dr. Watson in the Sherlock Holmes mysteries.) The Doctor regularly gains new companions and loses old ones; sometimes they return home, or find new causes on worlds they have visited. A few of the companions have died during the course of the series.
This list includes characters who appear to be human and who are not known to be anything other than human, even if having originated extra-terrestrially.
The Doctor Who comics, novels and audio dramas have created companions, villains and supporting characters of their own. Some of these originated in one medium and later appeared in another. The lists below indicate where a character has appeared.
Skaro is a fictional planet in the British science fiction television series Doctor Who. It was created by the writer Terry Nation as the home planet of the Daleks.
The Silurians are a race of reptilian humanoids in the long-running British science fiction television series Doctor Who, who first appeared in Doctor Who in the 1970 serial Doctor Who and the Silurians, and were created by Malcolm Hulke. The first Silurians introduced are depicted as prehistoric and scientifically advanced sentient humanoids who predate the dawn of man; in their backstory, the Silurians went into self-induced hibernation to survive what they predicted to be a large atmospheric upheaval caused by the Earth capturing the Moon.
Doctor Who Magazine is a magazine devoted to the British science fiction television series Doctor Who. Launched in 1979 as Doctor Who Weekly, the magazine became a monthly publication the following year. With 13 issues a year, as well as producing triannual deluxe Special Editions (2002–) and Bookazines (2013–), the publication features behind the scenes articles on the TV show and other media, as well as producing its own comic strip. Its founding editor was Dez Skinn, and the longest-serving editor was Tom Spilsbury who served from 2007 to 2017. He was succeeded by Marcus Hearn, who took over from Spilsbury in July 2017. The incumbent editor is Jason Quinn, who took over from Hearn in September 2023. DWM is recognised by Guinness World Records as the longest running TV tie-in magazine, celebrating 40 years of continuous publication on 11 October 2019. The magazine published its 600th issue on 1 February 2024.
Doctor Who spin-offs refers to material created outside of, but related to, the long-running British science fiction television series Doctor Who.
Ian Chesterton is a fictional character in the British science fiction television series Doctor Who and a companion of the First Doctor. He was played in the series by William Russell and was one of the members of the programme's first regular cast, appearing in much of the first two seasons from 1963 to 1965. In a film adaptation of one of the serials, Dr. Who and the Daleks (1965), he was played by Roy Castle, but with a very different personality and backstory. Ian appeared in 16 stories and 77 episodes. He later returned for a cameo appearance, played once again by Russell, in the 2022 episode "The Power of the Doctor".
Barbara Wright is a fictional character in the British science fiction television series Doctor Who and a companion of the First Doctor. She was one of the programme's first regulars and appeared in the bulk of its first two seasons from 1963 to 1965, played by Jacqueline Hill. Prior to Hill being cast the part had originally been offered to actress Penelope Lee, who turned the role down. Barbara appeared in 16 stories. In the film version of one of the serials, Dr. Who and the Daleks (1965), Barbara was played by actress Jennie Linden, but with a very different personality and backstory, which includes her being a granddaughter of "Dr Who".
Susan Foreman is a fictional character in the British science fiction television series Doctor Who. The granddaughter of the Doctor and original companion of their first incarnation, she was played by actress Carole Ann Ford from 1963 to 1964, in the show's first season and the first two stories of the second season. Ford reprised the role for the feature-length 20th anniversary episode The Five Doctors (1983) and the 30th anniversary charity special Dimensions in Time (1993).
The Doctor is the protagonist of the long-running BBC science fiction television series Doctor Who. They are a alien Time Lord that travel in the universe and in time using a time travelling spaceship, the TARDIS, often with companions. Since the show's inception in 1963, the character has been portrayed by fourteen lead actors. The transition to each succeeding actor is explained within the show's narrative through the plot device of "regeneration", a biological function of Time Lords that allows a change of cellular structure and appearance with recovery following a fatal injury.
The Tenth Doctor is an incarnation of the Doctor, the protagonist of the British science fiction television series Doctor Who. He is played by David Tennant in three series as well as nine specials. The character has also appeared in other Doctor Who spin-offs.
The First Doctor is the original incarnation of the Doctor, the protagonist of the British science fiction television series Doctor Who. He was portrayed by actor William Hartnell in the first three series from 1963 to 1966 and the tenth anniversary story The Three Doctors from 1972 to 1973. The character would occasionally appear in the series after Hartnell's death, most prominently as portrayed by Richard Hurndall in the 1983 multi-doctor special The Five Doctors, and as portrayed by David Bradley in the 2017 Twelfth Doctor episodes "The Doctor Falls" and "Twice Upon a Time" and in the 2022 Thirteenth Doctor episode "The Power of the Doctor", the latter previously having portrayed Hartnell himself in the 2013 biopic An Adventure in Space and Time.
Dr. Who is a character based on the Doctor, the protagonist featuring in the long-running BBC science fiction television series Doctor Who.
The Daleks are a fictional extraterrestrial race of mutants from the British science fiction television series Doctor Who. The mutated remains of the Kaled people of the planet Skaro, they travel around in tank-like mechanical casings, and are a race bent on universal conquest and destruction. They are also, collectively, the greatest adversaries of the Time Lord known as the Doctor, having evolved over the course of the series from a weak race to monsters capable of destroying even the Time Lords and achieving control of the universe.
The Time War, also called the Last Great Time War, is a conflict within the fictional universe of the British science fiction television series Doctor Who. The war occurs between the events of the 1996 film and the 2005 revived series, with the Time Lords fighting the Daleks until the apparent mutual destruction of both races. The war was frequently mentioned when the show returned, but was not directly seen until the show's 50th anniversary special.
The Eleventh Doctor is an incarnation of the Doctor, the protagonist of the British science fiction television series Doctor Who. He is played by Matt Smith in three series as well as five specials. As with previous incarnations of the Doctor, the character has also appeared in other Doctor Who spin-offs.
In the long-running BBC television science fiction programme Doctor Who and related works, the term "companion" refers to a character who travels with, or shares adventures with, the Doctor. In most Doctor Who stories, the primary companion acts as an audience surrogate by providing the lens through which the viewer is introduced to the story, and often, the series itself.
"The Beast Below" is the second episode of the fifth series of the British science fiction television series Doctor Who. It was written by executive producer and head writer Steven Moffat and broadcast on BBC One and BBC HD on 10 April 2010.
The Ninth Doctor is an incarnation of the Doctor, the protagonist of the British science fiction television series Doctor Who. He is portrayed by Christopher Eccleston during the first series of the show's revival in 2005.