Eldar are an ancient Xenos race that predates humanity and Chaos. They are all psychically active and have some of the most advanced technology in the galaxy. After the War in Heaven and the Fall of the Eldar, they are a shadow of their former selves.
The War in Heaven Edit
Fall of the Eldar Edit
Gathering Storm Edit
Eldar Gods Edit
The Eldar pantheon once had far more members, but by the 41st millennium only a handful survived:
Eldar Factions Edit
The Eldar split into the following groups:
Craftworld Eldar Edit
Most Eldar live on the craft worlds, massive world-ships that were able to escape the Eye of Terror. They live disciplined lives known as "paths" as a means to keep Slaanesh from hungering for their souls. When they die, their souls are captured in spirit stones and added to the craftworld's infinity matrix. Those on the Path of the Warrior are called Aspect Warriors, and will specialize in various different tactics. The Eldar also have a militia called Guardians, and spirit-powered automatons called wraiths. Those who specialize in psychic powers are Warlocks, with the mightiest becoming Farseers able to see into the future.
The Emperor is fine in theory with Eldar, if it weren't for the fact that they're smug assholes who want to put humans in zoos.
Dark Eldar Edit
Those Eldar who had escaped into the Webway founded their own city called Commorragh, and not only did they continue their hedonistic ways, they discovered that torturing others would temporarily keep Slaanesh away from their souls. As such, they've taken to slaving and piracy, becoming a scourge for innocent populations. However, they have also psychically atrophied.
The Emperor refers to the Dark Eldar as "completely unnecessary" and a bunch of "coked-up BDSM enthusiasts."
Harlequins serve the god Cegorach, and act as diplomats for the other Eldar factions. They are entertainers, historians, and cunning warriors. Cegorach protects their souls from Slaanesh, save for the Solitaires, who are doomed to lose their souls.
In TTS, the High Lords call Harlequins "clown goblins" and attempted to make them illegal for repeatedly breaking into the Imperial Palace.
The Exodites were among the first to realize how much trouble the Eldar Empire was in, and exiled themselves onto the maiden worlds. Their technology is less advanced than their cousins, but they have mastered using the native flora and fauna of their planets to stave off invaders. They also use their own version of the infinity circuit, a crystalline structure built into the planet that allows them to control its wildlife.
Eldar Corsairs Edit
Craftworld Eldar who want to break free of the disciplined ways of their people will choose the path of the exile, and will become adventurers and pirates. This lifestyle is quite risky as they have no protection against Slaanesh, though they will frequently aid their homeworld in times of need. Either they return home once their wanderlust is sated, or they become Dark Eldar.
With the birth of Ynnead, Eldar from all walks of life gathered to him to serve and fight against Slaanesh.
The Ynnari do not yet exist in TTS as the story content for Gathering Storm has yet to take place.