Watcher (Logopolis)

Prior to regeneration, Time Lords were sometimes visited and observed by a being known as a Watcher (TV: Logopolis, et al.) Observer, or shayde. (PROSE: Divided Loyalties) Sometimes merging with the Time Lord during regeneration, (TV: Logopolis, AUDIO: Winter) Watchers were the unregenerate forms of future incarnations (AUDIO: Trial of the Valeyard) or projections of alternative versions of the Time Lord. (PROSE: Divided Loyalties) A normal Watcher existed in a protoplasmic pupate state, (AUDIO: He Jests at Scars...) having "no real substance" but "an essence of what was and what will be". (PROSE: Divided Loyalties)

The Fourth Doctor witnessed his own Watcher before regenerating into the Fifth Doctor. (TV: Logopolis, PROSE: Into the Silent Land) While the Sixth Doctor claimed to have only seen a Watcher once, (AUDIO: Trial of the Valeyard) the Doctor later encountered Watchers during their regeneration into the Sixth Doctor (AUDIO: Winter) and in their tenth incarnation. (PROSE: The Advent of Fear)

The Sixth Doctor once speculated that the Valeyard was a Watcher, albeit one that looked nothing like ordinary Watchers. (AUDIO: Trial of the Valeyard) In another universe, Vansell and a Time Lord President were certain that the Valeyard was the first known Watcher to be thinking, self-aware, and independent. (AUDIO: He Jests at Scars...)

Rallon's Watcher, the Observer, merged with the Celestial Toymaker after Rallon's death. (PROSE: Divided Loyalties)

Shortly before Romana II regenerated from exposure to the Eye of Harmony, a Watcher-like figure was seen lingering around the Capitol. (AUDIO: Renaissance) However, after Romana left the Matrix, this regeneration was negated. (AUDIO: Ascension)

Immediately before her regeneration, Mullion saw her own Watcher on the other side of a lake. Convinced that it was actually her future self come to paradoxically kill her as she had killed her past selves, Mullion was distracted trying to kill the Watcher when she was murdered by Hole. (PROSE: What Keeps Their Lines Alive)

Behind the scenes

 * The animated scarecrows imbued with Time Lord power to execute the Second Doctor parallels the Watcher's powers. (COMIC: The Night Walkers)
 * K'anpo Rimpoche's Cho Je is similar in function to the Watcher. (TV: Planet of the Spiders)