Portrayed by: The TARDIS, Suranne Jones
Doctor(s): All of ‘em
Tenure: Pretty much all of ‘em
Background: The TARDIS (so named by Susan as an anagram of Time And Relative Dimensions In Space) is a Type 40 time travel capsule stolen from Gallifrey by the First Doctor when he decided to head out with Susan to explore the universe (or ran away, depending on who you ask and when). Though magnificent to the audience’s eyes, and the Doctor’s, most Time Lords consider Type 40s to be rather ramshackle, far from the most advanced or desirable model. It has a history of breaking down to varying degrees. Its chameleon circuit for example, which instantly disguises it to match its surroundings, has been set on ‘60s London for most of the show’s run, though it’s implied both the Doctor and the TARDIS itself are rather fond of this setting and would choose it regardless. Much like the Doctor, the TARDIS seems to regenerate at various points, taking on new control room designs, both based on the Doctor’s preferences and perhaps its own as well.
Family/Friends: There are many TARDISes in the classic series, but just as the Time Lords are all but gone in the modern series, making the Doctor the last of his kind, the rest of the TARDISes are time locked as well and the Doctor’s TARDIS is now unique in the universe. The TARDIS and the Doctor share an incredibly close bond, with varying levels of psychic linking with him throughout the show’s run, and they are the closest each has come to having a life-long partner.
Personality: The TARDIS is loyal, adventurous, and protective. When the soul of the TARDIS is put into Idris, allowing it to speak verbally, it takes credit for their adventures, claiming it had stolen the Doctor (rather than vice versa) so they could explore the universe. It can be finicky and seemingly unreliable, but in the most desperate situations, the TARDIS usually finds a way to do what is needed. Along with its devotion to the Doctor, the TARDIS has varying levels of affinity for his Companions, perhaps most notably not particularly warming to current Companion Clara.
Special Skills: Space time ship, ability to trigger and aid in the Doctor’s regeneration, non-linear sense of time, allowing the TARDIS to take the Doctor where and when he is most needed
Best Story: “The Doctor’s Wife” gives the TARDIS voice, finally letting it and the Doctor share a conversation, and that alone makes it the best story for the TARDIS
Worst Story: Attack of the Cybermen. It’s just weird to see the TARDIS actually have a (somewhat) functional chameleon circuit
“I wanted to see the universe, so I stole a Time Lord and I ran away. And you were the only one mad enough.” “The Doctor’s Wife”
The Doctor: “You didn’t always take me where I wanted to go.”
The TARDIS: “No, but I always took you where you needed to go.” “The Doctor’s Wife”
“I’ll always be here. But this is when we talked. And now, even that has come to an end. There’s something I didn’t get to say to you. … Hello, Doctor. It’s so very, very nice to meet you.” “The Doctor’s Wife”
Other notes: For a more in-depth look at the TARDIS’s construction, history, and room makeup over the show’s run, check out the excellent article about it at the TARDIS Data Core. Along with making the TARDIS briefly humanoid, “The Doctor’s Wife” manages to feature the TARDIS (‘s soul, inside Idris) traveling as a passenger inside the TARDIS (‘s body), making it fulfill one of the two major requirements for classification as a Companion- a.) traveling inside the TARDIS with the Doctor, b.) from one story to another. It’s the TARDIS, it’s been in the show from its very first moments. We’ll let it fudge the second criterion.