Initially, they were the Space Skaven, and garnered little attention. Then along came Xenology, an out-of-print Black Library book which detailed the findings of an Inquisitor on his pan-galactic, semi-heretical travels to understand what makes aliens tick; mostly by probing, disemboweling, dissecting, and doing generic alien-abduction-type things to random xenos scum. In his travels, he encountered the Hrud, a jellyfish-like race of decaying spine-creatures, and that is how GW sees them now. The Hrud managed to avoid the axe, and skirted the edges of unpopularity to such an extent that GW actually gave them a face-lift as 40k became less Warhammer Fantasy in space and more grimdark, unlike their long-lost brethren the Squa- *BLAM*.
Now, if only GW could get off its ass and make an army for them. They're definitely high up on the "most popular army-less races" list.
"Apparently, the Hrud's original homeworld was in a region of space the Eldar warned the Adeptus Mechanicus' Explorators to avoid, but the Explorators did not trust the xenos' warning and entered the star system anyway, precipitating the first contact between humans and Hrud sometime during the Great Crusade in the 31st Millennium. Classified as a hostile alien species after they destroyed the Explorator mission to their homeworld, the Astartes of the Iron Warriors Legion undertook a xenocidal war against the Hrud warrens on Gugann during the Great Crusade that nearly exterminated the species. However, Iron Warriors garrisons also suffered defeats at the hands of the Vulpa Strait migration of Hrud on Krak Fiorina, Stratopolae, and the Fortress World of Gholgis in the final years of the Great Crusade, proving that the Hrud remained a threat to the Imperium."
Yep, sounds about right.
The Hrud are a nocturnal race of scavengers and parasites. The Hrud are known to be very mysterious, many know of them, and few know about them. Imperial mothers scare their kids by telling them that a Hrud will steal all of their left socks or something if they don't eat their soylent-paste. Hrud have a very strong connection to the warp, which manifests as the "ssaak", or see mist, an aura of darkness which surrounds the Hrud in question. Hrud can slip through narrow spaces with ease, and their ssaak have a chameleonic affect that lets them hide by surrounding themselves in shadow or pretending to be a torchiere lamp. Once, a captive Hrud was able to conceal itself in a fully lit, white-walled cell. This ability could be created by the Hrud warp connection, their chemical poisons, or biological light-tricks; nobody knows for sure. Hrud are also silicon-based, which is actually possible.
The Hrud religious beliefs state that the Hrud were created by a benevolent pantheon of gods, known as the "Slah-haii", meaning "most ancient", which included a Horned God, Red Handed God, Artisan God and a Laughing God who all intended for the Hrud to live in sunlight and plenty...
Well, somebody just couldn't stand for happiness in the grimdark future, so the Slah-haii were beset upon by the "Yaam-khek", or Mirror Devils, who proceeded to boil, mash, and stick the Slah-haii in a stew of curbstomp and death, at "coincidentally" (wink wink) about the same time as the Eldar gods were being similarly raped. All, of course, but one, Qah. Qua figured out that grimdark meant grimdark for everybody, and turned the Hrud into nocturnal scavengers to have them avoid being similarly bawleeted.* Qah then told the Hrud that he had better things to do for a while, and he would be back when the time came for the Hrud tribes to unite and take down the Yaam-khek for good. This of course was a blatant lie, as he went not two minutes before meeting Slaanesh in the same dark alley that he/she/it met Khaine in. Qah was then shattered into a bajilion pieces by Slaanesh and banished into the realm between the Warp and realspace, but outside of the Webway. *The Hrud would use this same strategy of hiding in a hole to avoid Games Workshop's Axe of +9001 Retconing.
Being near the Hrud is a thoroughly unpleasant experience, as they have an entropic field which will age, decay, and pretty much wreck all nice things within the vicinity at an accelerated rate. Hrud can extrude a wide multitude of poisons from their bodies, and this eventually becomes a prevalent fog in the air of Hrud-infested areas. For humans who grow up in or near these places, these poisons will become adapted to, and eventually create a chemical dependency. Said humans will suffer withdrawal if deprived. If a Hrud is killed, its body will rapidly liquify, making dissection and study difficult, at best.
Things get really weird when you learn that they aren't migrating through space they're migrating through time. So it's entirely possible that all the Hrud encountered are the same individuals manifesting in different time periods (and incidentally may actually be heavily degenerated humans). This also means they don't exactly die since they exist at several points in time at once. "Kill" one, and it'll continue to exist in the past and future like nothing happened.
It's anyone's guess as to whether they're migrating forwards or backwards, though- even the Black Library authors who came up with the fluff confirming all this can't agree. And of course, there's the matter of what could be so horrible that they'd need to indulge in time travel just to get away from it...
In a weird twist, Hrud are both technologically advanced and technologically backwards. While the average Hrud is covered in rags, and would rather hide in a dark corner than build a house, the Hrud race are fantastic at reverse-engineering and scavenging. Unlike the Orks, who can durr and hurr their way to a Plasma Cannon, Hrud actually know how things work. That's more than can be said of even the Adeptus Mechanicus. Due to the lack of ammunition and repair facilities, the Hrud usually end up wielding whatever weapon they stole fused with their own technology (which looks more industrial, ancient and slimy than a Forge World)
When they don't want to steal something, they use what are called Fusils, which are warp-plasma muskets. The plasma moves between the Warp and realspace to bypass armor and shields. This same technology was used to make Warp Cores used by the squats. When the Mechanicus tried to tinker with the same technology, they DATA EXPUNGED a whole planet (Ganymede). Inquisitor Kryptman claimed that Hrud Fusils are a synthesis of Melta and Plasma technologies and use a lance-like beam to chew through armor, but he probably mistook another Hrud weapon for the Fusil.
Hrud weapons are both common enough (Hrud are everywhere) and useful enough (does your plasma ignore cover?) that they tend to end up in all sorts of strange places. They find their way to Inquisitors, assassins, alien mercenaries, small dogs, what have you.
General Hrud technology is compact, and in-between Orky contraptions and Imperial gadgetry in reliability. They make heavy use of both the Warp and standard technical knowledge in their machines, creating an aesthetic that is similar to both a gritty techno-industrial mess and the ancient artifacts from Skyrim, because Emperor knows you cannot get enough Skyrim.
What the Hrud are up to now
Hrud commonly live in underground cities called Juunlaks, made of tunnels, dirt, and dark. Juunlaks are found near centers of population in the host civilization, but never in very large numbers. Because the Hrud couldn't care less about what they leech on to, Juunlaks and/or Hrud infestations have been found on, but not limited to: Imperial Hive Worlds, Ork Worlds, Space Hulks, large Battleships of all races, the planet of Es'Tau, and Craftworld Saim'Hann. Eldrad was known to have eliminated the Hrud present on Saim'Hann, likely because he wanted to have the nice things on Saim'Hann that the Hrud would have made unhaveable. Due to the frequency of nomadic Hrud infestations on Imperial ships and Hrudite physiology, Imperial crews have given Hrud the hilarious and thoroughly Rogue Trader-esque nickname "Bendies." Most races consider them vermin, and use words like "infestation" to describe places where Hrud gather. They will try to exterminate them, but Hrud usually keep to themselves, and rarely, if ever, wage war on other races.
The Hrud believe that ancestry and family-ties are all-important, and they keep immaculate records on nearly everything. They are a tribal race, and shy away from contact with other Hrud tribes and empires. Conversely, single Hrud will flock together to form new tribes or join pre-existing ones. Record-keeping is a huge part of Hrud society, to the point where Hrud records are more reliable than Imperial records, and more precise than those of the Eldar. Even Hrud legends and folklore and religion are, when not fully factual, referencing true events. This mass-memory is somewhat fractured, as different tribes maintain records about their branch of the Hrud species, and when tribes split, they take copies of the pertinent information and carry on from there. This is not a terrible problem, though, and the totality of the records make the history of the "Raheed", or "masstribe."
Every so often, a Hrud tribe will reach critical mass and split, one half executing a Peh-ha, or mass migration. This is probably because they have become too populous, and must split to avoid detection. And presumably to get way from that one uncle who always wants to play Monopoly at family reunions. The irony is that once they leave, everyone and their grandmother steers clear of them. That many Hrud in one place can seriously mess you up, and in combat they are usually covered in shadow, and invisible until they're two feet away from you with a stolen pistol to your skull. Large enough migrations are known to start ruining whole planets worth of nice things from orbit.
On planets, they mainly survive on petty thievery, power-sapping, and mostly being a filthy xenos parasite. They do get hired on occasion as assassins, but they never hang around long enough to be anything more than a reputable killer for one-off jobs. Hrud are known to adopt humans or members of other races into their tribes and Juunlaks, where they are treated as zanhaads, or slave/pet/whatevers. Unfortunately the constant exposure to Hrud emanations and toxins means that the zanhaads develop a chemical dependency on them, ensuring that few run away.
- From 935.M41 to 938.M41, Ursarkar E. Creed fought the Hrud.
- Hrud are kind of awesome when their migrations get large enough, citing a 101.M40 record wherein a mass-migration forced a whole Freeboota Klan off-track to Haakonath, the homeworld of the Star Phantoms Space Marine Chapter. When the marines swiftly dispatched the Ork threat, the Hrud came down in full force, dragging with them a temporal-warp rift that was made from their collective entropy fields. This caused so much derp on Haakonath that the Star Phantoms had to retreat and lose their homeworld, making them "one of only a handful of Chapters who survived a full-scale Hrud migration alone."
- In 783.M41, the Hrud caused the Infestation of Ursula Spinal, an event which led to three full regiments of Valhallan Ice Warriors to age until their standard-issue balls of steel fell off.
An old-style Nocturnal Warrior of the Hrud. Also an Ambul.
The first Hrud model, from the old days.
An actual model of a modern Hrud. Use of Green Stuff was kept to a minimum.