Craftworld

Craftworld Biel-tan.

Craftworlds are massive, self-sufficient Eldar vessels, essentially mobile cities made of Wraithbone flying through space.

History

During the height of the Eldar Empire, the Eldar built the Craftworlds as large merchant ships. Somewhat questionably for traders, they didn't install any sort of Webway or Warp drives on the Craftworlds, instead forcing the Craftworlds to travel at sublight speed. Ultimately, this would be to the Eldar's benefit, for the amount of time spent between Eldar worlds allowed the Eldar on the Craftworlds to see just how far their people had fallen into hedonism. Realizing that something bad would happen soon, the Craftworld Eldar evacuated the Eldar still sane enough to realize how far they'd fallen from their depraved brethren, and fled, taking with them the repositories of Eldar history, science, and religion.

Unfortunately, Not all of them made it out of the Segmentum Obscuris in time, and were caught in the creation of the Eye of Terror just as the hedonists were. So grimdark.

Today, the Craftworld Eldar comprise the largest populations of surviving Eldar. They have similar goals in preserving the Eldar, reestablishing their Empire, and fighting Chaos. However, the Craftworlds often disagree over how to achieve these things. This can lead to small conflicts between the different Craftworlds, but for the most part these are rare.

Tabletop

Back in the third edition of Warhammer 40,000, Games Workshop released Codex: Craftworld Eldar, a "mini-dex" expansion booklet for the Eldar codex. It included five army list variants for the craftworlds Alaitoc, Biel-Tan, Iyanden, Saim-Hann, and Ulthwe. Each Craftworld receives a few unique units, and some receive army-wide special rules, a re-assignment of the available squads between the various categories (Troops, Elites, etc.), or even a different force organization chart. In the later Codex: Eye of Terror (released for the 2003 "Eye of Terror" summer campaign), Ulthwe got another mini-list for their "Strike Force".

Unfortunately, the Eldar got hit with the "less-is-more" bat in Fourth Edition, so the only difference between the Craftworlds on the tabletop throughout Fourth and Fifth Editions was that they had different colors and symbols. However, with the new Sixth Edition Codex, Games Workshop has bowed to fan demands seen an opportunity to make more money, and released a codex supplement all about Iyanden (unfortunately, it was written by none other than Your Spiritual Liege, and it shows). Presumably, the other "big five" Craftworlds (and similar supplements for other codexes, perhaps) are on the way. STOP PRESS! Supplements for other 6th Ed. races to date are as follows: Chaos Marines: Black Legion eBook (WHY?! WHY NOT THOUSAND SONS OR IRON WARRIORS?!?!), Tau Empire: Farsight Enclave... well, that's it for the minute.

Notable Craftworlds and specialties

The big five

• Alaitoc -- Follow the Eldar Paths more strictly and therefore have less fun. This leads many to become arrogant outcasts and eventually veteran rangers and pathfinders. They are also archenemies of the Necrons, and fight the zombie-bots on a constant basis.
• Biel-tan -- Wish to reclaim the old Empire of the Eldar before it got screwed over. Almost everyone is arrogantly warring with the lesser races. The best part? They honestly believe that the Eldar Empire still stands and that everyone else are squatters to be removed. Funny, considering that next to none of the populated worlds in the Galaxy ever had anything to do with the Eldar, meaning it wouldn't be theirs to begin with. This Craftworld is notable for being even more arrogant than most other Eldar. Even other Eldar have difficultly dealing with them. Biel-Tan is fiercely protective of Exodite worlds, and are known to reserve a special hatred for Orks, who are especially hard to exterminate from any planet they've managed to get a foothold on. In the original Dawn of War, Macha was from Biel-Tan.
• Iyanden -- Got OM NOM NOM NOM'd so almost everyone is dead. Fields lots of Wraith-units. Known for their Spiritseers, necessary for an army like theirs.
• Saim-Hann -- Jetbikes all day erryday. Considered barbarians by some other Craftworlds.
• Ulthwé -- They're a few inches away from the bleeding asshole of reality (which is why it's nicknamed "Ulthwé the Damned") so everyone is extensively trained for war, even the regular Guardians, who are called "Black Guardians". Also, this is where that dick was born. Also home to a pair of well-known Farseers.

All the others

• Altansar -- The home of Phoenix Lord Maugan Ra. Once thought lost in the Warp, Maugan Ra managed to find them and guide them out. Not very liked by the other Eldar, because they (rightfully so) think that nothing can remain untouched by the Warp.
• Il-Kaithe -- On an eternal crusade against Chaos, they are unusual in that they take their Bonesingers into battle, likely because how overpowered these dudes are.
• Iybraesil -- A matriarchal society that likely employs large numbers of Howling Banshees. They have a great interest in the Crone Worlds.
• Lugganath -- BFFs with the Harlequins, they think that the Galaxy has gone down the crapper (no shit, Sherlock) and want to start anew in the Webway.
• Kher-ys -- Destroyed by a Slaaneshi daemon incursion. Ohh, and a Keeper of Secrets possessed their Avatar during the fighting, you can imagine how much proverbial buttrape happened there.
• Malan'tai -- Got LOLDRAIN'D by a unique Zoanthrope who feeds off psychic energy. Needless to say, after it devoured the souls on the Craftworld's Infinity Circuit, things went very bad for them. Are now extinct. Grey Knights went and saved the remaining soul stone form a Keeper of Secrets.
• Mymeara -- Has an Imperial Armour book named after them detailing their fall.
• Yme-Loc -- Munchkin motherfuckers who spam grav-tanks and Titans in battle.
• Numinor- Home of the Eldar/Astartes hybrids known as Arcadians.