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The Witness, also known as the Entity, or the Voice in the Darkness, is an individual who appears to be the leader of the Black Fleet. It is described by Savathûn, the Witch Queen as a "child of the Darkness," and seems to act as its foremost representative in the physical universe.
The Witness is a tall, pale-skinned humanoid being. Most of its features are obscured by its metallic robe-like clothing, which constantly ripples and shifts seemingly of its own accord. Its long black cloak emanates the same resonance as other Darkness artifacts have done. Among its most notable features is a column of white “smoke” that is continually billowing from the top of its head, which forms a multitude of humanoid faces as it spreads and dissipates. Its true face is partially concealed, but it can be seen to have large, dark eyes and a rectangular pattern of gray lines on its brow and forehead.
The Witness is an extremely powerful wielder of the Darkness, perhaps more so than any other being in the universe. It is evidently capable of using the Darkness to move entire planets between realities, causing them to disappear from the "normal" universe into some other realm, possibly the Ascendant Plane; this is suggested to be a more refined application of the same powers that enable the creation of Taken. When Mars reappeared in the Sol System after having vanished following the arrival of the Pyramids, the surface of the world was covered with patches of terrain that appeared to have been temporally displaced, showing Mars as it had been at various points in the past.
At times the Witness leaves a series of “afterimages” of itself while in motion; for example, when moving its arms, multiple ghostly silhouettes of its arms will repeat the gesture after a delay. The significance of this is unknown but may be related to its apparent time and reality manipulation abilities.
When speaking, the Witness is either speaking to some other entity(s) or it is referring to itself as a plurality (using the word “we” instead of “I”).
The Ancient Past
The history of the Witness is almost totally unknown. Contradictory statements from Savathûn claim both that the Witness was once a mortal creature whose race was empowered by the Darkness and that the Witness itself birthed the Darkness; the latter statement is almost certainly a falsehood, as Savathûn in other contexts has described the Witness as a "child of the Darkness," and the Darkness has stated itself to have existed for eternity. What is known is that it has existed in the universe for eons, during which it has acted to further the aims of the Darkness, or at least its own interpretations of them.
The Recruitment of a Disciple
Billions of years ago, the Witness visited a dying world called Lubrae, which had degenerated into a military dictatorship after the Traveler had blessed and left their civilization. There, it encountered a warrior named Rhulk, who had fallen into a chasm after being betrayed by his family and clan. The Witness healed Rhulk's injuries and gifted him a remade and empowered version of his Glaive, and told him that his destiny was to bring ruin to Lubrae. Rhulk went on to massacre the people of the city above the chasm, and eventually destroyed his entire planet by using the Upended to destroy Lubrae's Sapphiric Sun. As Rhulk fell once more into the chasm, the Witness saved him again by bringing him aboard its Pyramid. There, it converted Rhulk to worship of the Darkness by showing how, from the perspective of the Darkness, the lives that had been lost on Lubrae were never worth anything to begin with, and that he had proven his worth by destroying them and surviving the extinction of his species by his own hand. This caused Rhulk to swear himself to the Witness as one of its Disciples.
Subjugation of the Worms
The Birth of the Hive
The Witness played a key role in the ascension of the Hive on Fundament by telepathically communicating with the young Sathona via her Worm familiar, telling her that the Osmium Court was in imminent danger of destruction by a tidal wave generated by a syzygy. In reality, there was no such danger: the Witness merely wanted to claim the Krill as servants of the Darkness before the Traveler could arrive and uplift them along with the Ammonites. 
The Witness had a direct role in the Collapse, alongside its Disciples and Savathûn, the Witch Queen. According to Savathûn's Worm, the Witness intended to destroy the Traveler during this event, but was somehow tricked by Savathûn into allowing the Traveler to survive. As a result of this deception, the Witness and its Black Fleet returned to intergalactic space, where they would remain for centuries before the Traveler made its continued existence known at the end of the Red War.
When Eris Morn awakened the Pyramid beneath the Moon, the Darkness emanating from it reached out to the Guardian investigating her whereabouts and began to invade their Ghost.  When they return equipped with Dreambane Armor, the Pyramid invites the Guardian inside where whispers of the Witness' presence could fully possess their Ghost. It is there the Voice in the Darkness coldly denounces the Light as a weakness which had brought only death to those it "blessed", citing the Great Disaster, the Red War, and the death of Cayde-6 as examples of its numerous failures. Once the Guardian reached the statue at the center of the Pyramid, they are offered the Unknown Artifact as "respite", granting them a vision of the Black Garden. It is there that the Witness reveals themselves to the Guardian having taken their form against a backdrop of the Black Fleet. The Witness addresses the Guardian having heard humanity's cries for help and that they would soon answer, claiming that they are neither friend nor enemy, but instead their "salvation".
Return to Sol
Upon arriving in the Sol system once again with its Black Fleet, the Witness used its powers to cause Mars, Mercury, Titan and Io to vanish from the universe, transferring them to an unknown plane of reality. Before Io's disappearance, the Witness instructs the Guardian to travel to Europa to seek out an ancient power, which they do receive while dealing with the Eliksni under House Salvation using Stasis as well. Mars would later return under mysterious circumstances, but with regions of its surface having been temporally displaced.
The Awoken Queen Mara Sov encountered the Witness beyond the heliopause of the Sol system. There, it showed her a vision of the impending future upon its arrival, and subsequently offered the Awoken Queen the opportunity to become one of its Disciples. The Queen refused and fought the Witness and its armies throughout the ascendant plane before returning to the Dreaming City.
After Savathûn, the Witch Queen was reborn in the Light, only to have her plan to steal the Traveler thwarted by the Guardians, the Witness addressed the Traveler, declaring that it had "seen enough" and would take action to "save" the denizens of Sol.
List of appearances