The Watcher (Logopolis)

The Watcher was a manifestation of the Doctor who appeared a few hours before the regeneration of his fourth incarnation into his fifth. He appeared to the Doctor himself and his companions and brought Nyssa to the planet Logopolis.

Biography
The ghostly figure of the Watcher had a white, featureless, unformed face and body and white clothes. Though he would use The Doctor's TARDIS later, he apparently had the power to traverse time and space without external aid.

He was first seen silently observing events on Earth, particularly the events leading to Tegan Jovanka entering the Doctor's TARDIS. It was around this time that the Doctor first noticed the Watcher.


 * It is not known for how long the Watcher had been observing the Doctor.

Although silent, the Watcher was capable of communication. He communicated with the Fourth Doctor and, later, his companion, Adric. The Watcher, apparently on his own accord, transported Nyssa from Traken, a planet which would soon die in the entropy wave, to Logopolis and safety. Later, apparently working on the Doctor's instructions, he piloted the TARDIS from Logopolis to keep Adric, Nyssa and Tegan safe. It was during this voyage that the Watcher engaged Adric in a private conversation.

At the moment of the Fourth Doctor's death, the Watcher appeared and merged with the Doctor to create the Doctor's next incarnation. (DW: Logopolis)

In a dream, the Fourth Doctor saw the Watcher and thought of his next incarnation. (ST: Into the Silent Land)

While regenerating into his next incarnation, the Fifth Doctor again saw the Watcher. (BFA: Winter)

Behind the scenes

 * In the novelisation of Logopolis, the fact that the Watcher was the Doctor was indirectly alluded to during the TARDIS scenes where Nyssa and Adric were being taken away from Logopolis by the Watcher, allegedly at the Doctor's request. While the Watcher was never heard to speak on-screen, the novelisation suggests that Adric and Nyssa could hear him, possibly by telepathy. Both of them find the voice familiar, but are unsure why they recognise it. When Adric tries to remember the Watcher's voice, he finds he can only recall the Doctor speaking.
 * The nature of the Watcher's conversations with the Doctor and Adric was never revealed. Logopolis suggests that the Doctor was made aware of his impending regeneration due to his statement "It's the end, but the moment has been prepared for." The knowledge passed to Adric is never revealed, although after the transformation, Adric does show an unexpected knowledge of regeneration in Castrovalva.
 * Several other "partial Doctors" have appeared in the history of the series, most notably an evil manifestation, the Valeyard.
 * The Watcher of the Doctor's old friend Rallon appeared in Divided Loyalties, merging with the Celestial Toymaker – who had possessed Rallon's body for his own – after Rallon's death to keep the Toymaker in check in future, the transition from Rallon to his Watcher causing the Toymaker's personality to change as though he himself had regenerated. This Watcher was known as the Observer.