The character known as the Doctor’s wife in the 2011 episode is Idris.
In “The Doctor’s Wife,” the entity House removes the TARDIS’s matrix—the ship’s consciousness—and places it inside the body of a woman named Idris, played by Suranne Jones. For the first time, the Doctor can speak directly with the personality of his time machine, which has taken human form through Idris.
Idris is therefore more than an ordinary companion or guest character. She is the TARDIS itself, temporarily embodied as a woman. Her relationship with the Doctor is affectionate, argumentative and deeply familiar, reflecting their centuries of travelling together. The episode’s title uses “wife” in a playful, metaphorical sense rather than identifying a legal spouse.
Amy Pond and Rory Williams are the Doctor’s actual travelling companions in the episode. River Song is also closely connected to the Doctor, but she does not appear in this story. Clara Oswald belongs to a later period of the programme.