The Ninth Doctor was a direct survivor of the Last Great Time War, but left the conflict with the excruciating knowledge of his hand in its grisly conclusion. Now cut off from the Time Lord race, the Doctor found himself alone and bereaved. Emotionally haunted by the war's apparently catastrophic outcome, he entered a darker period of his life spattered by resentment, where he tended to brood and act crossly to those who rubbed him the wrong way. Despite this, he remained jovial and quite friendly towards anyone he took a liking to, slowly reasserting himself as the Doctor while letting go of his lingering wartime persona.

Rose Tyler was his most constant companion, although he did share several adventures with Jack Harkness as well. During the Slitheen's attempt to destroy the Earth for profit, he gained temporary allies in Rose's mother Jackie, Rose's ex-boyfriend Mickey, and Harriet Jones. He also had a single adventure with Adam Mitchell, an employee of Henry van Statten, at Rose's request, but evicted him for almost dramatically altering human history.

He regenerated after he directly absorbed time vortex energy that had converted Rose briefly into the Bad Wolf entity. Though this saved her, it caused massive damage to his body at the cellular level.

Companions:

Rose Tyler, Adam,Captain Jack Harkness