User:Epsilon the Eternal/Sandbox Sixteen

By some accounts, ∂³Σx² was the Doctor's true name. (INFO: The Making of Doctor Who, Marvel Premiere 57) The name, also inscribed upon K9 Mark 1's regeneration unit, resembled (TV: Regeneration) Old High Gallifreyan, the archaic language used in the Time of Rassilon. (TV: The Five Doctors)

Curiously, the name was inscribed inside the Tomb of Rassilon, seen by the First, Second, and Third Doctors. (TV: The Five Doctors)

Other accounts indicated that "Dr. Who", abbreviated regularly to just "the Doctor", was the Doctor's actual name. (COMIC: The Klepton Parasites, et al, more to be added)