Great Intelligence

The Great Intelligence, which usually referred to itself simply as the Intelligence and was originally known as Yog-Sothoth, was a disembodied sentience who attempted to find a body and physical existence.

Existence
In the universe before this one, Yog-Sothoth had a body that was a mass of tentacles and mouths. (PROSE: Millennial Rites) Like the other Old Ones, it may have lost its body when it ran from the Fendahl. (PROSE: White Darkness) Afterwards, the Intelligence constantly sought physical existence to replace being a shapeless, formless cloud hanging in space. (TV: The Web of Fear)



The Intelligence possessed several people as its main instruments, namely Padmasambhava (TV: The Abominable Snowmen), Staff Sgt. Arnold (TV: The Web of Fear), Edward Travers (HOMEVID: Downtime), and Walter Simeon (TV: The Snowmen). When not using a living being, it maintained a basic manifestation as a three-sided pyramid of control spheres (TV: The Abominable Snowmen) or an ivory pyramid. (HOMEVID: Downtime) When forcibly summoned to Earth by Anne Travers, and being combined with three sets of physical laws in the Great Kingdom, the Intelligence was an emerald tetrahedron and, because of Travers's meddling, was merged with the god Saraquazel. (PROSE: Millennial Rites)

Biology
The Great Intelligence possessed some amount of artron energy. (PROSE: Millennial Rites) At some point it became a swarm of "living snow;" carnivorous, multi-nuclear crystalline organisms which generated a low level telepathic field that could detect and respond to thoughts and memories, mimicking and mirroring whatever it found and feeding off thoughts to learn what it could. This snow-form seemed independent, with some ice crystals forming mindless predatory snowmen and a perfect duplicate of human DNA in ice form, while the main Intelligence remained separate. Thoughts affecting a critical mass of snow could affect all the snow, leading to the loss of this body when the snow turned to rain.

In its many attempts to achieve form, the Intelligence tried to manifest as ice people based on the human form (TV: The Snowmen) and a slime that glowed brightly with a piercing light. (TV: The Abominable Snowmen) It manifested as a dense fog that consumed anything entering it, and a poisonous web/fungus which spread through the London Underground and trapped the Doctor's TARDIS. The web could not be destroyed by chemicals, explosives, or flamethrowers. (TV: The Web of Fear) A fourth invasion of Earth had it trying to perpetuate itself in every machine and being, with the whole planet cocooned in web: one mass of thoughts in one global body. (PROSE: Downtime)

What was it?
The Great Intelligence's exact nature is a mystery. Described as a mind parasite by Lethbridge-Stewart, it was described as a mass of thoughts with a single thought. It once reflected on whether or not it remembered what its original body was:

"Was it huge with massive claws to crush and maim? A bloated spider-mind filling every cavernous gap with billowing web? Was it a mountain? A bank of mountains looming and rumbling like clouds in another sky or on another continuum?"

- Downtime

Powers
The Great Intelligence had no physical existence and thus relied on possession of living creatures and other shapes in order to manipulate its environment. It existed on the astral plane and could enter the people it encountered. It allowed Padmasambhava to live over 300 years while he created Robot Yeti (TV: The Abominable Snowmen) and it also reanimated the dead (or near-dead) bodies of Staff Sergeant Arnold and Professor Travers (TV: The Web of Fear) feeling itself into every cell and having control of every movement. At full strength it could even save a human from fatal illness.

The Great Intelligence could manifest itself in simple forms such as a slime that glowed brightly with a piercing light, a dense fog that consumed anything that enter it, and a poisonous web/fungus that could not be destroyed by chemicals, explosives, or flamethowers.

In addition, it could possess animals like rats and ants by extending its will as well as inhabiting machinery like computer terminals. It resided in the New World University network while reaching out into the Internet, but was still trapped in the campus mainframe.

It had considerable mental powers, namely telekinesis. It was able to make a Eurotrain rear up like a snake and launched missiles, playing with them and engineering near-misses before letting them fall. (PROSE: Downtime) It could also create servants from the material around it. (PROSE: Millennial Rites) It also tracked the Doctor and followed him through time and space, having built a machine that could drain his mind of knowledge and experience for the Intelligence. (TV: The Web of Fear)

Personality
The Intelligence thought very highly of itself, informing the Doctor that his brain was too small to grasp its purpose. (TV: The Abominable Snowmen) It also sometimes referred to itself as "we." (TV: The Snowmen) Without a body, it became obsessed with having physical form, craving symmetry of light, colour, and shape. The Intelligence thought that revenge was a petty emotion which it had no need for.

It was the unseen but generous Chancellor of New World University, with Victoria as Vice-Chancellor. It designed invasions based on a "Great Plan" it had, having been the military strategist of the Old Ones, and when it thought resistance was useless for humanity, it asked Brigadier Lethbridge-Stewart which part of its brilliant plan he found most effective. (HOMEVID: Downtime) When horribly bound to Saraquazel, it did not care about him or crave his assistance, thinking it possessed enough power and intellect to find its own escape. The Intelligence, however, did warn Saraquazel of the duplicity of human beings. (PROSE: Millennial Rites)

Early history
Yog-Sothoth was a being who existed before the universe in which the Doctor resided. It was a member of a race of beings called the Great Old Ones, who were the equivalent of the Time Lords. They shunted themselves into a parallel universe/dimension to pass into the next universe. Yog-Sothoth discovered he had gained god-like powers and being the military strategist of his people, the Great Intelligence decided to try the various gambits and games he had only played on computers. Over the billennia he mounted millions of campaigns against inhabited planets. He used the Hisk version of Koala bears on Hiskith and domestic animals equivalent to dogs on Danos. Though the Yeti had failed to take over Earth, he was under pressure from the other Great Old Ones, who themselves embarked on similar campaigns and conquered other planets, forcing him to use the Yeti in London, an environment to which they were not well suited. (PROSE: Millennial Rites) The Intelligence had been exiled from another dimension, and was forced to wander the universe to find a body to possess. (PROSE: Doctor Who and the Web of Fear)



Pre-20th century
At some point, the Great Intelligence possessed the Tibetan lama Padmasambhava while he was travelling the astral plane and forced him to build its Robot Yeti over the next centuries. (TV: The Abominable Snowmen)

In the 19th century, the Intelligence made a parallel attempt to destroy Earth, manifesting as living snow that used Walter Simeon as a host whose dark thoughts powered it. He established the Great Intelligence Institute as the snow slowly swarmed to Earth over 50 years, and in 1892 was sufficient enough to consume mankind. Having erased Simeon's mind, the Eleventh Doctor was surprised to see the Intelligence survived, thinking it was created by the host Simeon, but it had learned to survive beyond physical form. It was stopped in the last minutes of Christmas Eve when the snow was drowned by replicating the tears of Captain Latimer's family under Clara Oswald's care at her death. During this encounter, the Eleventh Doctor inadvertently facilitated the Intelligence's later (or earlier, from the Doctor's perspective) attack in the 1960s by showing it a schematic of the London Underground, providing it remembered his comment that the Underground was a strategic weakness in the metropolitan area. (TV: ''The Snowmen)

20th century
In 1935 at the Det-Sen Monastery, the Second Doctor and Edward Travers, a westerner determined to find the Yeti, interviened with the Intelligence's plans and destroyed the pyramids that controlled its Yeti. Padmasambhava's physical body died when the Intelligence melted away. (TV: The Abominable Snowmen)

Thirty-five years or so later, the robot Yeti re-activated and the Intelligence manifested as webbing. It ensnared the Doctor's TARDIS in space and forced it to land in the London Underground. Reunited with Travers, the Doctor assisted British military in their battles with the Yeti. The Intelligence re-animated and possessed the corpse of Staff Sergeant Arnold, using him to track the Doctor's actions. The Intelligence captured the Doctor and tried to use a conversion headset to take over the Doctor's body. The Doctor attempted to reverse the process, allowing him to absorb the Intelligence and destroy it. When the control spheres that formed the focus of the Intelligence were smashed by Jamie McCrimmon, the Intelligence vanished, powerless but still alive. (TV: The Web of Fear) With everything reversed, it was blinded in unending darkness.



The Intelligence later contacted the Doctor's former companion Victoria Waterfield and manipulated her into using computers to return to physical existence in 1995, attempting to cover the Earth in web. When the generators to the New World University were destroyed, the main bulk of the Intelligence faded away. (HOMEVID: Downtime)

The Intelligece was flung back into the void, where it could recover from the damage done to its being. In 1999, Anne Travers, who had been left traumatised by the Intelligence's first attempts to enter the universe, believed millionaire Ashley Chapel would try to use a special program, the Millennium Codex, to summon the Intelligence to Earth. She prepared a counterspell to force it back into its own reality. However, this had destructive effects, including dragging the Intelligence back to Earth and merging it with the benevolent god Saraquazel into a single malevolent being. It altered reality around London to form the Great Kingdom, a realm partly obeying the laws of the Intelligence's universe, this universe, and Saraquazel's universe; here, the Doctor's TARDIS was worshipped as "the Lady TARDIS" and the Intelligence was worshipped as "the key and the guardian of the gate," forming the triad of gods with Saraquazel. Anne sacrificed herself to fix reality, but instead of destroying the Intelligence and being no better than it, she banished it. The Intelligence became stranded on the edges of the universe, riding the blue shift outwards into infinity. (PROSE: Millennial Rites)

Other encounters
The Seventh Doctor, Lysandra Aristedes and Sally Morgan encountered the Great Intelligence during their travels in the black TARDIS. (AUDIO: Black and White)

Behind the scenes

 * Yog-Sothoth is the name of a fictional deity created by H. P. Lovecraft. The name first appears in The Case of Charles Dexter Ward. It was implied to be one of the most powerful beings in the universe (second to only Azathoth) and described as existing outside of the space-time continuum in a place where it exists at every point in time and space.
 * Writer Neil Gaiman disclosed in Doctor Who Magazine that earlier drafts of his script for The Doctor's Wife implied that House, the villain of that story, was actually the Great Intelligence. These hints did not make it into the episode as aired. The idea of the Great Intelligence as a villain for the revived series Doctor Who would later lead to TV: The Snowmen.
 * With a gap of forty-four years, the Great Intelligence holds the longest period of time where it has not appeared in televised Doctor Who. Following the Great Intelligence is the Macra with forty-years, and the Axos with thirty-nine years.

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