The Dark Eldar are kindred to the Eldar, an ancient and advanced race of elf-like humanoids. Their armies usually have the advantages of speed and technology, though they are often lacking in resilience and numbers. The Dark Eldar revel in piracy, enslavement and torture, and are sadistic in the extreme. Dark Eldar raiding parties make use of advanced anti-gravity skimmers to launch high speed raids on their enemy while still transporting a large number of their warriors. Due to their use of the galaxy-spanning inter-dimensional labyrinth known as the Webway, they are extremely mobile, striking from seemingly nowhere, with little or no warning, and vanishing with their captives before significant military reaction can be mobilised.
The Dark Eldar are unique amongst the races in the sense that they do not occupy many planets, but rather one dark city called Commorragh. They are mainly pirates, though are sometimes used as mercenaries.
Asdrubael Vect is the supreme overlord of the dark city of Commorragh and of the Dark Eldar as a whole. The term "Dark Eldar" also comes from him, being the first one to openly refer himself with "Eladrith Ynneas" in M32.[1c]
The origins of the Dark Eldar can be found in the Fall of the Eldar, the great cataclysm that nearly destroyed the entire Eldar race. It was an event so terrible that not only did it kill trillions of Eldar, but it breached the gap between real space and the Warp, and gave birth to Slaanesh, a Chaos God.
To understand the reasons for the Fall, it is necessary to know something of the Eldar mind and soul.
An Eldar's mind is incredibly complex. Their senses are extremely sharp, able to perceive incredible levels of detail. Their emotions can be so strong that a human's are merely pale shadows by comparison. They are extremely intelligent; their thought processes are much faster than a human's. All of this means that an Eldar experiences the universe and all its sensations to a greatly heightened degree. Similarly, an Eldar's soul is much brighter in the Warp than those of "lesser" sentients. Eldar are able to affect the nether-realm much more than most other races. They are all latent psykers and have the ability to become very powerful with training. It is the strength of their souls that was one of the causes of their downfall. Before the Fall, the Eldar had an immense galaxy-spanning empire comprising millions of worlds, larger and more powerful than even the Imperium of Man at the height of its power. The Eldar lived in relative peace - barbarian races such as the Orks were kept at easily manageable numbers and never had the strength to threaten the might of the Eldar empire. The humans were not yet virulently xenophobic and did not have a large domain, and the Tyranid Hive Fleets were unknown. The C'tan and Necrons, ancient foes of the Eldar, were long ago defeated and still remained dormant.
Life on the Eldar Worlds was idyllic, with fantastically sophisticated machines to take care of all labour and manufacturing required, leaving the Eldar free to indulge in other, more aesthetic pursuits. With all menial work taken care of for them, the Eldar became indolent and decadent. They began to explore more and more the arts of pleasure, delving ever deeper into hedonism. This descent into decadence spanned millennia. Tradition and order disintegrated, as they limited the pursuit of pleasure. Sects called Pleasure Cults were formed, dedicated to achieving the highest levels of hedonistic sensation, and their ceremonies and practices became ever more wild, eventually devolving into violence and sacrifice of their own kind. Some Eldar hated what their race had become and left the homeworlds for the virgin Maiden Worlds, or left on the newly-constructed Craftworlds, leaving the Pleasure Cults to their madness. During this time the Eldar had also discovered the Webway and soon mastered it to further their galaxy-spanning civilization. Building realms and outposts within the Webway to act as ports for inter-galactic travel, the city of Commorragh was founded. Isolated within the Webway, Commorragh itself soon became a bastion for pleasure cults and increasingly depraved acts.[1b]
Meanwhile, something terrible was stirring in the Warp. The millennia of Eldar hedonism had made a massive impact in the psychic realm of Chaos. Within the warp the decadent Eldar civilisation was giving shape to a Power of Chaos, which grew and grew over thousands of years, getting stronger and more defined until suddenly it sparked into an intelligence - a shatteringly huge and malign intelligence, with an immense and bottomless thirst for Eldar souls. This was the birth of Slaanesh. The process lasted for thousands of years, corresponding to mankind's Age of Strife, although when Slaanesh finally came into being, the results with the universe were apocalyptic and sudden. An almighty psychic shockwave scythed across the galaxy. The souls of almost every Eldar were stripped from them in an instant and devoured by the new-born Chaos god. There were few survivors. Most were driven mad, their minds trapped half in the real world and half in the swirling insanity of the Warp. A great Warp rift was created, encompassing the entire Eldar empire and creating the Eye of Terror.
The denizens of Commorragh, however, were tucked away safely in the Webway, protected from Slaanesh and its thirst. Though much of the Webway was in ruin, they had endured and, unlike their Craftworld counterparts, remained unrepentant. Though they discovered Slaanesh was still slowly claiming their souls, the denizens of Commorragh soon discovered that by absorbing the pain and torments of another's soul they could rejuvenate themselves and cheat death. Assuming they could feed regularly, the Eldar of the webway had become physically immune to the passage of time. Soon the Eldar of the Webway began raiding Realspace in search of captives and slaves to rejuvenate themselves with. So it was that the Dark Eldar were born, a race of sadistic murderers who feed upon the anguish of others to prevent the death of their immortal souls.[1b]
Dark Eldar are similar in many ways to the rest of the Eldar race - tall, lithe, humanoids with tapered ears and sharp eyes.[1a] However, generations of physical conflict combined with living inside the Dark City has led to a number of distinct variations. The skin of a Dark Eldar is almost translucent, an effect of the lack of sunlight within Commorragh.[1a] A Dark Eldar's strength and reflexes are actually superior to that of a Craftworld Eldar[1a] - pict-captures of the Evolus Massacre had to be slowed to one-fourth speed in order to follow the movements of individual Kabalites as they slaughtered Imperial civilians.[5b] Stories of Dark Eldar dodging shots from lasguns and kicking frag grenades back into the enemy's ranks are common,[5b] and within the gladiatorial arenas a single Wych is more than a match for any ten human warriors. Dark Eldar senses are also sharper, allowing them to see their enemies perfectly well even during pitch darkness.[5a]
However, Dark Eldar psykers are virtually unheard-of. The innate psychic abilities common to the Eldar race have atrophied within the Dark Eldar, partly due to their focus on physical athleticism. Furthermore, to use any psychic powers would draw the attention of Slaanesh, and is one of the few things expressly forbidden within Commorragh.[1a]
Dark Eldar, like most Eldar kindreds, make use of advanced technology, including anti-gravity devices, dark matter weaponry, nanotechnology and psychic artefacts. However, this technology is manufactured instead of being psychically grown, and while Dark Eldar do make use of psychic devices, they do not use psychic powers themselves, for in order to use their gifts Psykers must channel the chaotic energies of the Warp. Such an act would attract the gaze of She Who Thirsts and invite disaster upon the entire race. As such, the use of the psychic pyrotechnics that are so familiar to their Craftworld kin is one of the few things forbidden in the dark spires of Commorragh [1a].
Over time, Dark Eldar begin to suffer more and more from The Thirst. They develop an all-consuming and ever-increasing need to drink the souls of other beings. It is postulated that the cause of this is the Chaos God Slaanesh, the Great Enemy of the Eldar, who leeches the soul-essence of the Dark Eldar while they still live. Dark Eldar drink souls to stave off this leeching - perhaps by sating the thirst of Slaanesh, or perhaps by replenishing the essence of their own souls with that of the consumed one. Slaanesh will also consume the souls of Dark Eldar whole should they die. Dark Eldar are long-lived but not immortal; drinking souls has a rejuvenating effect that reverses ageing, thus Dark Eldar need not fear falling into the clutches of Slaanesh due to death from old age, if they have a constant supply of souls. The usual source of souls is the many captives taken during Dark Eldar raids.
Notable Dark Eldar
- Arhra, the former leader of the Striking Scorpion Aspect Warriors and founder of the Incubi Warrior Caste.[1b]
- Aestra Khromys, Queen of Splinters, Archon of the Kabal of the Obsidian Rose.
- Asdrubael Vect, Supreme Lord of the Kabal of the Black Heart, and overlord of Commorragh.
- Aurelia Malys, Leader of the Kabal of the Poisoned Tongue. [1b]
- Decapitator, Mandrake Champion.
- Drazhar, the "Master of Blades", Incubi Champion. Believed by some to be Arhra. [1b]
- The pirate prince Kaharhaedros - an oddity among Dark Eldar he openly courts Slaanesh. He had a plan to create a new Commorragh, however, his plan failed when the Captain of the Second Company of the Crimson Fists eliminated his Incubi and foiled his plan. Kaharhadros later fell into a Warp hole he made and was destroyed.
- Archon Kesharq, of the Kabal of the Sundered Blade
- Lelith Hesperax, Leader of the Wych Cult of Strife.
- No'akei, the Daughter of Pain. Strike force leader on Medusa V.
- Baron Sathonyx The Lord Hellion.
- Tahril of the Kabal of the Black Heart. An Archon who leads the Dark Eldar throughout the Kaurava campaign. He has a certain hatred for the Farseer of Ulthwé.
- "Duke" Traevelliath Sliscus Commander of the Sky Serpents. [1b]
- Urien Rakarth, Master Haemonculi.
- Vhane Kyharc, Archon of the Black Myriad.
- Vraesque, Archon of the Kabal of the Flayed Skull.
- El'uriaq, the Tyrant of Shaa-Dom
- Vorsch, Haemonculus and demented genius 
- 1: Codex: Dark Eldar (5th Edition),
- 2: Warhammer 40,000: Dawn of War - Soulstorm
- 3: Soul Drinkers (Novel Series)
- 4: White Dwarf 372 UK
- 5: White Dwarf 311 UK
- 6: Codex: Dark Eldar (3rd Edition), pg. 44
- 7: Warhammer 40,000 4th Edition Rulebook, pg. 144
- 8: Warhammer 40,000 6th Edition Rulebook, pg. 207
- 9: Path of the Renegade (Novel) Chapter 1
- 10: Nightbringer (Novel) - The Ultramarines Omnibus by Graham McNeill, Chapter Four, pg. 71