The Eldar, or Aeldari as they were known in the Aeldari Lexicon before the fall of their lost realm, or the Asuryani (followers of Asuryan) as they refer to themselves, are an ancient humanoid alien species whose vast empire once extended the width and breadth of the known galaxy. The Aeldari Empire was without equal, and they counted themselves masters of the stars. But millennia ago, the Aeldari's overweening pride and their fall into hedonistic practices led to a cataclysm that all but eradicated their kind and led to the birth of the Chaos God Slaanesh. Despite their boundless power, the heart of their civilisation was torn out by this catastrophe of their own making, forcing the surviving Aeldari, now calling themselves "Eldar" to outsiders and "Asuryani" among themselves, to flee upon gigantic, continent-size starships called craftworlds. Now they cling to survival by a thread, fighting the horrors of the galaxy with ritualised discipline and consummate skill.
The Aeldari species has a long and complex spacefaring history, so long in fact that little is known for certain about the course of their physical evolution and early planet-bound existence. The original Aeldari homeworld was destroyed during the catastrophic collapse of the Aeldari civilisation known as the Fall of the Aeldari. The remnants of Aeldari culture that survived the cataclysm preserved much of their species' history in the form of traditional stories, songs and dance. Written records, monuments and visual records were almost completely destroyed except for a few instances where they were taken aboard voidcraft fleeing from the doomed worlds. As a humanoid race, Aeldari are physically very similar to Humans, although not entirely identical by any means. They possess longer and cleaner limbs, and fine ascetic features with penetrating and slightly slanted, almond-shaped eyes. Their ears are also slightly pointed, but otherwise they could pass as Human at first glance. The most obvious difference between Humans and Aeldari can only be seen when they move, for the movements of an Aeldari radiate a subtle grace which is impossible for a Human to emulate. This can be seen in even their slightest gestures or the dexterity with which they manipulate small objects. The Aeldari mind, while similar in general to the Human psyche, is far more inclined towards emotional extremes. Because of this, Aeldari are more intelligent but also far more intense than Humans. Although an Aeldari and a Human can both feel grief or joy, the Aeldari's experience is likely to be far more extreme. This natural inclination towards emotional extremes is both a blessing and a curse to the Aeldari. On the positive side, it gives them an unparalleled appreciation of life and an unrivalled ability to express themselves through music and other creative endeavours.
A melody or gesture made with grace and skill can elicit an intensity of pleasure which is unimaginable to a Human. But this potential for joy is paralleled by an equal capacity to feel despair, ambition and even hatred. Confronted by grief or other personal setbacks, an Aeldari suffers mental torments which far exceed the boundaries of Human anguish. The extreme nature of their temperament makes it very important that the Aeldari maintain a measure of self-control at all times, for it is dangerously easy for them to become entranced by and ultimately dependent upon the experiences that their culture offers them. They must learn to control the darker side of their natures, which is no less an essential portion of the Aeldari psyche -- and the source of the catastrophe that nearly caused their extinction. The Aeldari are a naturally psychic race, and all Aeldari possess the potential to become powerful psykers if they choose to pursue this path. The Aeldari can use these innate abilities to shape matter, which lies at the foundation of their extraordinary command of technology. Though highly advanced and feared across the galaxy, the Aeldari are still a dying people in the late 41st Millennium -- a shadow of their former glory -- and their species teeters on the brink of final annihilation.