Companion

Over the centuries, the Doctor has acquired numerous companions in his travels through space and time. Some appear to have travelled with him for years, others for just a few days. While these companions have included members of various species from different planets, most have been humans from the planet Earth, especially the 20th and 21st centuries. Most of these, in turn, have been young females. The earliest known companion of the Doctor was Susan Foreman, generally believed to be his granddaughter and a fellow native of Gallifrey. He has also had at least one fellow Time Lord as a companion (Romana - it is not known whether Susan was considered a Time Lord during her travels with the Doctor).

Not all of the Doctor's companions have been humanoid, as he has also travelled with a robot dog (K-9), a shape-changing android (Kamelion) and a shape-shifting alien who preferred to maintain the form of an earth penguin (Frobisher), among others. In an alternate timeline, the Doctor also travelled with a android recreation of The Master (DW: Scream of the Shalka).

Most evidence indicates the Doctor's relationships with his companions have been generally platonic in nature. There have been some instances where a relationship between the Doctor and a companion may have developed beyond simple friendship, but the only confirmed case of this (to date) has been the relationship between the Doctor and Rose Tyler (DW: Doomsday, et al, although only in Doomsday were these feelings articulated, at least in the case of Rose). At least three companions have indicated they had fallen in love with the Doctor, although the Doctor did not appear to reciprocate: Sarah Jane Smith (DW: School Reunion), Jack Harkness (DW: Utopia, et al) and Martha Jones (Last of the Time Lords, et al). The Doctor, for his part, once told Rose that he couldn't allow himself to develop such feelings, due to the reality that, as a Time Lord, he can expect to live for many more years, while a human companion would age and die. (DW: School Reunion)

Companions have come and gone in many different ways. Some, such as Rose Tyler, have been explicitly invited (DW: Rose); some have been unwilling adventurers, such as Ian Chesterton and Barbara Wright (DW: An Unearthly Child); while some have joined the TARDIS crew by accident, such as Dodo Chaplet (DW: The Massacre of St Bartholomew's Eve). A few individuals have been invited to join the Doctor in his travels, only to decline, such as Grace Holloway (DW: Doctor Who: The TV Movie) and (initially) Donna Noble (DW: The Runaway Bride), while others have been invited, but prevented from joining the Doctor due to their deaths, such as Madame de Pompadour (DW: The Girl in the Fireplace) and Astrid Peth (DW: Voyage of the Damned). There is at least one instance of a human performing the function of a companion without ever actually travelling with the Doctor: Sally Sparrow (DW: Blink).

Companions have also departed the Doctor for various reasons. Some have left after becoming disillusioned with the life of a time-traveller, such as Tegan Jovanka (DW: Resurrection of the Daleks), while a number of companions have departed in order to forge a new life in a new time or world, such as Vicki (DW: The Myth Makers), Mickey Smith (DW: The Age of Steel) and Susan Foreman (DW: The Dalek Invasion of Earth), although in the case of Susan the decision for her to stay was made by her grandfather. A few companions have left the Doctor due to Time Lord actions, such as Sarah Jane Smith (DW: The Hand of Fear) and Jamie McCrimmon (DW: The War Games). On one occasion, a companion has lost the privilege of travelling in the TARDIS due to bad behavior, when Adam Mitchell was evicted (DW: The Long Game). On a few rare occasions, companions have been killed while travelling with the Doctor, the first known fatality being Katarina (DW: The Daleks' Master Plan). After departing from a companion, the Doctor is rarely known to reunite with them, though there have been some notable exceptions, such as Sarah Jane Smith (DW: The Five Doctors and School Reunion), Martha Jones (DW: The Sontaran Strategem), Jamie McCrimmon (The Two Doctors), and Donna Noble, who received a rare second chance to travel with the Doctor after her initial refusal (DW: Partners in Crime).

Although not companions in the traditional sense, the Doctor has, from time to time, shared one-off adventures with notable figures in history, in which they function as companions. Examples include H.G. Wells (DW: Timelash), Charles Dickens (DW: The Unquiet Dead), William Shakespeare (DW: The Shakespeare Code), and Agatha Christie (DW: The Unicorn and the Wasp). In the case of Christie, the Eighth Doctor once claimed she actually travelled with him at one point (BFA: Terror Firma).


 * (For a full roster of the Doctor's companions see: List of companions).

Other Time Lords have been known to have companions in their travels. Before his final corruption into the renegade known as the Master, the Time Lord Koschei was accompanied in his hunt for the Doctor by Ailla. Koschei believed Ailla to be a young woman from a 28th century Earth colony, but she was in fact a Time Lady agent sent by the High Council to spy on the increasingly erratic Koschei's actions (MA: The Dark Path). In his battle with the newly regenerated Eighth Doctor, the Master was assisted by Chang Lee, a young man in 1999 San Francisco. Lee had been convinced by the Master that the Doctor was evil. Only too late did he learn the truth as the Master killed the boy, although the Doctor subsequently restored him to life (DW: Doctor Who: The TV Movie).

The Master took the Time Lord-companion relationship one step further by marrying his human companion Lucy Saxon, with every indication that a passionate relationship initially existed between them (DW: The Sound of Drums), only for it to turn abusive later, culminating in Lucy shooting and apparently killing her husband. (DW: Last of the Time Lords)

Noel Coward was a close friend and may even have been a travelling companion of the Time Lady known to the Doctor as Iris Wildthyme (EDA: Mad Dogs and Englishmen). When she left the Fourth Doctor in E-Space, Romana was accompanied by K-9 Mark II, and K-9 continued to be her companion after she returned to normal space (DW: Shada (webcast), et al)

Behind the scenes
The exact criteria for a character becoming a companion has been a matter of debate in Doctor Who fan circles for many years, with some choosing not to consider "one-off" characters such as Sara Kingdom or Grace Holloway to be companions. Also debated is whether recurring characters who share adventures with the Doctor but don't necessarily travel with him should be considered companions, such as The Brigadier, Mike Yates and, more recently, Jackie Tyler.