The Doctor's aliases

The Doctor has employed several different aliases, sometimes only briefly. He has often had aliases assigned to him by others.

John Smith
John Smith or Dr. John Smith was the alias the Doctor generally used as a name on the planet Earth.

Ka Faraq Gatri
The Daleks referred to the by this name, which may mean Bringer of Darkness and/or Destroyer of Worlds. By implication, the name Destroyer of Worlds refers to the Doctor's destruction of the Dalek home planet Skaro in his seventh incarnation, an act for which he would consequently feel some remorse. (NA: TImewyrm: Revelation) However, as eary as his second incarnation the Doctor knew that the Daleks had given him this name. (DWM: Bringer of Darkness)

Time's Champion
Time's Champion was a title given to the Doctor to symbolize his service to Time.

The Oncoming Storm
The Daleks refered to the Doctor as the Oncoming Storm in the myths of their homeworld, as noted by his ninth incarnation, indicating that the Daleks feared him (DW: The Parting of the Ways). This was also the name given to him by the Draconians, who were generally his allies, to indicate the traumatic events which so often accompanied his arrival. (NA: Love and War)