Ordo Hydra

The Ordo Hydra is an extremist offshoot of the Illuminati, and features in The Inquisition War series of novels by Ian Watson.

It is probably composed mainly, but not entirely, of Illuminati-Inquisitors. Its origins can be found in the pathological hate of Chaos by some Illuminati, coupled with the uncertain and very-long term timeline of the "mainstream" Illuminati's plans. The Ordo Hydra has conjured a warp-type entity called the Hydra, which is a supposedly benevolent mind/soul virus controlled by them. Their plan is to infect as many human worlds as possible, as soon as possible; through the mind-resident virus, they then plan to direct the uncountable infected humans into delivering a tremendous concentrated psychic blow to Chaos, which the Chaos Powers would presumably be unable to resist. The Ordo Hydra believes that this can happen much sooner than the timeline of the "long watch" of the "mainstream" Illuminati - at most, in a matter of centuries (as compared to the "watch", which could take millenia).

The "mainstream" Illuminati are trying to stop the Ordo Hydra's plan, as it would result in defacto mental enslavement of Humanity even if successful. There is also the possibility that the "rogue" Illuminati's plan will backfire, resulting in the creation of a fifth Chaos God, and in the complete domination of the Galaxy by the Ruinous Powers.