The Companions (general)
- Classic series companions (1963-1989, 1996)
- Revival series companions (2005 onwards)
- Other supporting cast
The term "companion" refers to a character who travels with, or shares the adventures of the Doctor. In most Doctor Who stories, the primary companion acts as an Audience Surrogate, providing the lens through which the viewer is introduced to the series. The companion character often furthers the story by asking questions and getting into trouble, or by helping, rescuing, or challenging the Doctor.
This designation is applied to a character by the show's producers and appears in the BBC's promotional material and off-screen terminology. Until the modern revival of the series in 2005, the term was rarely used on-screen; the Doctor tends to refer to the show's other leads as his "friends" or "assistants".
- Action Survivor: Bare minimum, just surviving at least one adventure with the Doctor promotes them to this.
- Anyone Can Die: Sometimes, companions aren't lucky enough to live through some adventures. Sometimes it's a Heroic Sacrifice, other times it's simply being in the wrong place in the wrong time.
- Audience Surrogate: Companions are designed in part so that viewers could relate to her depending on their age; when conceiving the series' first companions; Susan Foreman, Barbara Wright and Ian Chesterton, Susan, a teenager, was designed with younger viewers in mind, while Barbara and Ian, who were adults and Susan's schoolteachers, were targeted towards adults. Even the occasional alien or otherwise non-human companions tend to ask questions the audience would ask and say things the audience would say.
- Badass Normal: The companions that don't have the benefit of alien powers when helping the Doctor fight evil aliens.
- Badass Unintentional: Most companions are relatively normal until the Doctor walks into their lives. Through their adventures, though, they're given the chance to regularly thwart the horrors of the universe and save lives and planets.
- Bizarre Human Biology: Travelling with the Doctor through the Time Vortex alters them on a genetic level the results include mutated white blood cells and Ripple Effect-Proof Memory.
- Catchphrase: All of them are likely to say "It's bigger on the inside than the outside!" or some variant upon entering the TARDIS for the first time.
- Damsel in Distress: It isn't as if the Doctor or bystanders are immune, but the perils they tend to face means that companions get this right, left, and centre, regardless of their gender.
- Deuteragonist: They share the stories with the Doctor. They're all sidekicks, but according to some writers, they're the protagonist.
- Distressed Dude: It isn't as if the Doctor or bystanders are immune, but the perils they tend to face means that companions get this right, left, and centre, regardless of their gender.
- Fantastically Indifferent: Along with Unfazed Everyman. They have to get used to weirdness to keep up with the Doctor, but it's occasionally shown that this can be unsettling to bystanders.
- Fish out of Temporal Water: Regardless of whether they're from the present, the past, the future or another planet.
- Jumped at the Call: Particularly in the revival, where the Doctor seems to pick companions based on willingness to enter danger.
- Let's Get Dangerous!: Most companions have moments where they step up and save the day.
- Living Emotional Crutch: For the Doctor, especially in the revival. With the amount of trauma the Doctor's been through, you can see why.
- Morality Chain: They also stop the Doctor from doing something they'll regret later.Donna: Sometimes, I think you need someone to stop you.
- Only Child Syndrome: All the more obvious when families started getting more screentime in the revival.
- Plucky Girl: Most female companions either start out as this (like Clara and Dodo) or later develop into this (like Rose and Donna).
- Sarcastic Devotee: The vast majority of companions will often joke at the Doctor's expense.
- Unfazed Everyman: Most of them become this after one or two adventures.
- The Watson: Barring some rare examples, such as Romana and River (who are on an equal level with the Doctor), one of the duties of a companion is to ask the Doctor "what's going on?"
- What the Hell, Hero?: Most companions will call the Doctor out on some of his more unsavory aspects.