Aelves, once known as Elves in the World-That-Was, are one of the intelligent species who live among the Mortal Realms. They are tall, slender humanoids with pointed ears known for their potent, inherent magical abilities and extremely long lives.
The aelves have always been rare, a handful of Lion Rangers in their mountaintop monasteries, a solitary Loremaster in the White Tower, and almost all were originally found within Azyr, the Realm of Heavens.
A few proud nobles did forge kingdoms in the wider realms, but these were small holdings or else comprised entirely of other intelligent mortal species and ruled by an aelven elite.
Yet many aelves now call the Realms of Hysh and Ulgu home, though a large population can still be counted among the Free Peoples who live in Azyr and among the Cities of Sigmar founded in the Age of Sigmar.
Soon after their awakening in the Eight Realms, the four aelf Incarnate gods -- Teclis, Tyrion, Morathi and Malerion -- discovered the souls of their lost kin from the World-That-Was in had been consumed and incorporated into the essence of Slaanesh, and in the last days of the Age of Myth they enacted a plan to entrap the Chaos God and release the aelven souls it had greedily consumed following the End Times.
Thus began a late flowering of aelven civilisation in the Mortal Realms. But the aelven souls reclaimed in this way were no recreation of those who had been taken from the World-That-Was. They had been marked by their ordeal, and each would be influenced by the specific magic of the god who guided them towards rebirth.
The aelves born to Malerion, in Ulgu, the Realm of Shadows, are dark and terrible to behold. Those crafted of Hysh, the Realm of Light, by Teclis and Tyrion are numinous creatures of white light and soaring pride. The Scáthborn of Morathi, meanwhile, are serpentine or winged monstrosities, twisted by the vileness of their captor -- or perhaps their creator.
All aelves share physical characteristics, the signature tapered ears for example, as well as sublime physical grace and beauty. Aelves have an inborn sensitivity to the underlying natural forces of the realms, allowing them to adapt to extreme environments where even an orruk would struggle to survive.
This same inherent attunement to the realms fuels their natural affinity for the magic that defines each of the realmspheres. From the deep-sea-dwelling Idoneth Deepkin to the arboreal Wanderers, aelf and realm share an almost symbiotic bond.
Aelves are extraordinarily long-lived, although this too can vary between lineages. The Khainite Witch Aelves with their rejuvenating blood rituals are almost immortal, whereas an Idoneth would be fortunate to see the end of their third century of life.
All aelves, regardless of origins, are beings of lofty arrogance. This manifest sense of superiority can often appear as callousness or cruelty, but even the most benign regularly cross into condescension when dealing with "younger" species.
Aelves live long and varied lives. During their many years, most aelves seek a calling or focus to help ground them in the Mortal Realms. Some are drawn to study or a particular craft, while others hone their body to peak performance.
Whatever they choose, there is a ritual to it, marked by stages in learning and progression. These incremental steps are used as a tether to mark their place in the ever-flowing river of time.
Towards the end of the Age of Myth, the aelven gods found Slaanesh and hatched a plan to free the aelven souls from the Dark God's essence. Teclis, Tyrion, Malerion and Morathi worked together to drag Slaanesh into Uhl-Gysh and began extracting the souls from its stomach.
Following the Age of Chaos, the civilisations of the aelves split apart and diverged. The Highborn either retreated to Azyrheim or defended their own enclaves, while the Wanderers and Exiles travelled throughout the Mortal Realms. 
When the aelven souls were freed from the essence of Slaanesh, they were tainted by the experience of being part of the substance of the Chaos God and became something other than aelves. The souls free by Morathi were made by her into the Scathborn, such as the Melusai and Khinerai.
Any aelven souls that were too weak or corrupted became the leathanam, a class of worker slaves.  Teclis created the Cythai, but when they rejected his teachings they became the Idoneth Deepkin. 
Old Aelven Pantheon
- Khaine: Though Khaine was killed by the Chaos Gods, Morathi tricked the Daughters of Khaine, claiming that he was merely weakened and that they will be able to reconstruct him through worship and devotion . Morathi now held Khaine's iron heart, the only vestige of him in the Mortal Realms, yet the prayers and offerings of the Daughters power her instead.
- Mathlann: Mathlann saved the last of the aelven souls from the World before Time, but to no avail. He died alongside the last of Aelvenkind. The Idoneth Deepkin can channel the souls of their deceased people alongside old memories of him to summon the Eidolon of Mathlann. 
New Aelven Pantheon
- Alarielle: Though originally an aelf, Alarielle instead spends her time with the Sylvaneth.
- Tyrion and Teclis
- Warhammer Age of Sigmar - Soulbound - Core Rulebook (RPG), pp. 23-24
- 1: Battletome: Daughters of Khaine (2nd Edition)
- 2: Battletome: Idoneth Deepkin (2nd Edition)
- 3: Order Battletome: Sylvaneth (2nd Edition)
- 4: Games Workshop - Warscrolls Compendium: High Elves (PDF)
- 5: Games Workshop - Warscrolls Compendium: Wood Elves (PDF)
- 6: Games Workshop - Warscrolls Compendium: Dark Elves (PDF)