ARC

ARC (Autonomous Reasoning Center) was an alien creature imprisoned aboard a SERVEYOUinc research base. He was rescued by the Eleventh Doctor, Alice Obiefune and John Jones and traveled in the TARDIS with them. (COMIC: The Sound of Our Voices)

The ARC would at some point leave the TARDIS. (COMIC: Four Doctors)

Behind the scenes

 * ARC is both a playable character and an enemy in Doctor Who Legacy mobile game.