"Handles" was the name given by an Auton copy of Dorium Maldovar to a severed Cyberman head during a theft of the Maldovarium by Kiz the Head-Taker, Vertebrae and Agrakos. (PROSE: The Heist) The Eleventh Doctor eventually obtained Handles from the Maldovarium and subsequently repaired it. All of its organic components and Cyberman protocols had been erased, leaving it a plain, docile robot with a tendency to interpret commands literally, whether or not they were meant to be taken as rhetorical statements.

Handles became the only constant companion of the Doctor during his self-imposed exile on Trenzalore protecting the town of Christmas, during which period he eventually developed an irreparable fault and died, leaving the Doctor devastated. (TV: The Time of the Doctor)

Source of the description: https://tardis.fandom.com/wiki/Handles