The Fall of the Eldar is an event in the science fiction universe which provides the background story for the miniature wargame Warhammer 40,000. The fall is presented as an Eldar myth about how they caused the downfall of their own civilisation and an explanation for why they are so few in number at the time of the events which set the scene for Warhammer 40,000.
The Eldar were a technologically advanced race, considered one of the most powerful races in the entire galaxy. Their Empire spanned the Galaxy and no other race could challenge them, however their fall came not from the actions of another race but from within.
Their technology having advanced so far that little or no work was required by individual Eldar groups of Eldar formed cults dedicated to the pursuit of experiencing everything that life had to offer. These pursuits became more extreme and depraved as time went on. Groups of Eldar condemning this behavior began fleeing to the outer edges of the Empire becoming Exodites and forsaking technology as the only way to prevent the degradation of their way of life.
Government within the Eldar Empire soon collapsed and the degeneration of their homeworlds and colonies continued unimpeded. As the pursuit of ever more extreme experiences reached its height death reigned in the streets of Eldar cities, hunter and hunted each being part of a twisted ritual of destruction which abhorred thousands.
The deaths of hundreds of thousands of Eldar in extremely pleasurable and painful ways lead restless souls into the warp this build up caused great disturbances preventing other races from using the warp for travel. The unease within the warp built up to colossal proportions as the psychically charged souls of the Eldar fed a new entity, the Chaos god of Slaanesh. Within Eldar society it was only the large generational trading crafts which saw the decay but they were largely ignored as the cults permeated virtually ever layer of society, only a few great seers predicted what was to happen next. Some trading crafts fled from the Eldar worlds isolating themselves from the corruption forming the Craftworlds, completely independent societies.
The buildup of pressure within the warp eventually reached a critical point and Slaanesh was born, ripping a gaping hole between warp space and real space centered around the Eye of Terror, the birthing cry of Slaanesh ripped the souls of Billions of Eldar all over the galaxy from their bodies as the hungry god fed on its foolish followers. Some of the craftworlds were too late and were sucked into the eye of terror never to be heard from again. While others suffered many loses as Slaanesh consumed the souls of their inhabitants.
Slaanesh then began to consume the Eldar gods, all but two, the god of War Kaela Mensa Khaine whose form was pure and uncorrupted by Slannesh's great evil and the Laughing God. It is said that Slaanesh and Khaine fought for supremecy while the Laughing God hid behind Khaine for protection. In the end Slaanesh proved the more powerful and shattered Khaine into shards which rained down on the mortal world and came to rest at the centre of the Craftworlds, and the Laughing God fled to the Webway and continued to hid from Slaanesh.
Few Eldar survived the Fall, some Exodites living on far away planets were left mostly untouched while a number of Craftworlds also managed to escape. Groups of Harlequins within the Webway under the protection of the Laughing God (although whether they first appeared before the fall of after is unknown) also survived. Lastly a group of cultists managed to survive the fall by feeding Slaanesh the souls of others. They also fled into the Webway where they felt the tug of Slaanesh on their souls lessened, but not completely gone, they continued their cults of ecstasy killing and draining the souls of others to feed Slaanesh and prevent their own destruction.