The Valeyard

The Valeyard was an entity created between the Doctor's "twelfth and final regenerations", perhaps the essence of the Doctor's dark side from that time.

General Information
The Valeyard appears to be like any other Time Lord which allows him to insinuate himself into the Gallifreyan court system; the Valeyard however lacks his own regeneration cycle so can not be considered a true Time Lord. The Valeyard's lack of his own life cycle drove him to attempt to steal the Doctor's remaining lives (DW: The Trial of A Time Lord).

Biography
Little is known about the Valeyard's creation other than that it occurred between the twelfth and final regenerations of the doctor. The Valeyard subsequently becomes or impersonates a prosecutor in the Gallifreyan courts.

The Valeyard served as the prosecutor during the trial of the Doctor. He presented extracts from the Matrix depicting past events in the Doctor's life as evidence of the Doctor violating the non-interference policy of the Time Lords. Later in the trial he added a charge of genocide against the Vervoids (DW: The Trial of A Time Lord). The Valeyard had secretly tampered with the Matrix extracts to show the Doctor in the worst possible light and steer the trial to a guilty verdict. The Valeyard was acting on behalf of the High Council to cover up the Ravolox affair. As payment, the Valeyard was to receive the Doctor's remaining regenerations (DW: Trial of a Time Lord). It was The Master who stepped in and revealed that the Valeyard was actually the Doctor himself "between his twelfth and final regenerations" forcing an end to the trial.


 * The Master's statements seem ambiguous on this point, leaving many mysteries open concerning this statement.

The Valeyard escapes into the Matrix via the Seventh Door, which he opens using a copy of the Key of Rassilon. He is pursued and finally defeated by the Doctor when an explosion the Valeyard had intended to destroy the court is fed back into the Matrix due to the Doctor's tampering (DW: The Ultimate Foe).

The Valeyard is encountered again by the Doctor in London, 1888, where he is posing as Jack the Ripper.

Other timelines
In one timeline, the Valeyard did manage to defeat the Doctor and went on to wreak havoc throughout time and space. (DWU: He Jests at Scars...)

Behind the Scenes
The Emissary of Death was a story scripted for the unmade season 27 of the original run of Doctor Who. This story would have featured the return of the Valeyard, where he attempted to not only frame the Doctor for committing the Jack the Ripper murders, but also for breaking the laws of time by committing them two years early. The plot element of the Valeyard being Jack the Ripper would be reused in Matrix.