According to the record-keeping of the Hrud, they were an ancient race that predated the time when Mankind became the masters of space and their tribes have been living a parasitic existence for longer than what was known to humans.[1b] The Imperium of Man first encountered the Hrud as far back as the era of the Great Crusade. Early in this era the noisome warrens of these aliens were cleansed by the Emperor according to the Liber Historica Vangelia.[5a] During this time, the Iron Warriors Adeptus Astartes were in the midst of a cleansing of Hrud warrens on Gugann.[9a] After formation, the Inquisition became the first institution aware of emergent menaces to the Imperium such as Necron awakenings, the arrival of Tyranid hive fleets and the advent of Hrud migrations. Numerous Hrud infestations are known to have plagued the region of the Maelstrom alongside more than twenty Ork empires and countless human pirate strongholds.[5b] At some point, the Hrud are known to had infested Mortenken's World. They were driven from the holy city by the hands of Daenyathos, a legendary philosopher soldier of the Soul Drinkers. Around seven hundred and thirty years ago the Ultramarines battled the Hrud in the Battle of Ortecha IX which saw Battle Brother Olfric perish. He would be avenged by his comrades that ate the heart of his killer.
In 980.M35, a major Hrud war against the Imperium took place known as the Hrud Rising. The infestations led to the Dark Angels Chapter being deployed against them, but after clearing two of the designated three sectors they withdrew for their own mysterious reasons. 
In 101.M40, a Hrud migration forced an Ork Freeboota Klan from the Edge Void to desperately send their forces at the world of Haakonath where they engaged the Star Phantoms Chapter. The Space Marine forces fought against the Ork attackers and eliminated them thus believing that they had achieved a victory in the defence of their homeworld. However, the Hrud threat began to manifest with a vast temporal-warp rift that was surging into the star system from the outer void. At its vanguard came the massive Hrud migration force that were trapped within the rifts event horizon. Despite putting up a valiant defence, the Star Phantoms were fighting a lost cause. Every misshapen Hrud struck down after coalescing from the shadows was replaced by another dozen, distorting space with their very presence. The presence of the Hrud had notable impacts on Haakonath. The Astartes were forced to evacuate their homeworld, and they remain one of only a handful of Chapters who survived a full-scale Hrud migration alone.[9b] A number of Hrud were present on Es'Tau and were encountered by the Last Chancers when they infiltrated the Tau Empire as mercenaries.
A notable engagement with the Hrud came in 783.M41 during the Infestation of Ursula Spinal. The agri-world became subject to a migration. It quickly became infested with its plantations of hydro-crops turning to dust and its defenders aging fifty years over the span of a few months due to the Hrud's innate entropic fields. To combat the threat, six regiments of Valhallan Ice Warriors made planetfall in order to purge the colony from the infestation. However, a full half of the regiments suffered premature aging due to contact with the Hrud and were declared unfit for further duty.
In 0.257.790.M41, a Hrud managed to infest the Emperor Class Battleship Paternus Gloriem. Indentured crewman Selebor Mathias managed to knock it unconscious, whereupon he was interrogated by the Inquisition with the specimen taken for study.[1a] Farseer Eldrad Ulthran is known to have participated in the prevention of a Hrud infestation of Craftworld Saim-Hann which would have reduced the proud vessel to rotten mulch. The Ordo Xenos Inquisitor Helynna Valeria is known to have treated with Eldar, Ulumeathi, Draxians, Hrud and scores of other xenos species in order to expand humanity's stores of knowledge.
In 844.M41, the Cinchare Hrud Infestation led to engagements with the 39th Cadian of the Imperial Guard on Cinchare [10a] This conflict saw the Hrud engage the 1st Company of the Dark Hands Chapter.
Between 938-985.M41, Commander Ursarkar E. Creed is known to have fought a Hrud migration.[10b] At some point, Hrud infested the Delphic mines of Mordant Prime leading to the conflict known as the The Plague of Delphic. The 303rd Mordant Acid Dogs engaged the aliens and managed to eliminate them but they suffered heavy losses in the process.
Physically, Hrud tend to be impossible to study as they wear ragged cloaks which they wear habitually and helps conceal their true form. This is namely a misshapen morass of decomposing filth though it is known that they have a female gender.[1b] They have been depicted as being a a crouched, diminutive creature swathed in rags, its face obscured by a hood, and possessing a rat-like tail. It seems that the Hrud prefer darkness and are basically scavengers and tunnel-dwellers. They are found all over the galaxy, though never in large numbers. They are considered to be parasites, and when they are referred to it is usually as "infesting" a place. In addition the limbs of a Hrud have a bone structure similar to the human spine allowing the limbs to bend in any direction (hence the nickname "bendies"). They also exude various poisons from their skin. Their bodies liquefy rapidly upon death - conveniently making detailing the creature impossible.[1b]
The bodies of this species is known to be perfectly adapted to the life of opportunistic predators and they are able to synthesize a staggering array of different poisons. Any humans that were adopted by a tribe tended to adapt and live on these poisonous emanations. Thus, their departure can leave a human that had lived amongst them to die in a state of toxic shock as their bodies became deprived of these poisons. In addition, they are able to slip past even the most narrowest of tunnels. Furthermore, they generated what they called a "ssaak" or "see mist" which is a distortion field that is actually biologically generated from their bodies which allows them to confound the eyes of any enemies. Many outsiders did not know whether this ability was a physical ability, a property of the chemicals they produced or simply a trick of the light. What is known is that the Hrud tend to be shrouded in darkness, even when in a cell with full light they are able to conceal themselves. This is why their species became known as "shadow creepers" and that legends spoke of them being nearly invisible.[1b]
Another notable quality amongst the race is that they produce innate entropic fields from their bodies. This has the side effect of aging their surroundings leading to objects such as crops turning to dust due to prolonged exposure and Humans suffering from premature aging. These time distorting fields are capable of wreaking havoc on entire worlds during mass migrations which are caused by the simple presence of the Hrud.[9b] Should a sufficiently powerful migration of Hrud coalesce, their temporal powers can extend from time, to space itself. During their invasion of Haakoneth Hrud forces were able to conjure a temporal rift that slew many Star Phantoms with cruel angles of distortion and even blinded the Chapter Master Omadon Tiresias when a rogue time eddy speared through the bridge of his Battle Barge's Command Deck. 
This mysterious species are noted as being a nocturnal race who are one of a number of Xenos breeds attracted to darkness. From the interrogations of a Human slave that served the Hrud, its known that they are a secretive race of subterranean scavengers who lived in tunnel-cities known as "juunlak"s. These typically are formed near the greatest centres of Human population. They tend to be fiercely tribal and are expert scavengers of technology to the point that they can easily assemble from a mongrel collection of weapons and devices with the resources they have at their disposal. Ancestry and family-ties are two elements that are considered all-important in Hrud society which defies the "filthy scavenger" image that Imperial scholars view the xenos species. Outsiders tended to never doubt the existence of the Hrud though not much was known about them by humans with rumours speaking of secret societies of these aliens living onboard ships though they tended to be used as bogeymen to scare infants. Hrud have demonstrated a unparalleled fastidiousness in the field of record-keeping where they compile vast stores of historical, cultural and technical information.[1b]
During times of population growth, this species is known to undergo what they called a "peh-ha" which is a mass migration. Once the population of a tribe reaches as a particular level of saturation, the Hrud members begin to form a schism as they separate from one another. These individuals begin to stow aboard transports and Space Hulks in order to begin the formation of a new tribe at a distant site. Among the items they take is the amassed knowledge of the "Raheed" which is the "masstribe". Entire nomadic nations of such Hrud have flourished on the areas between decks on board Imperial vessels. According to the findings of Inquisitor Ryal Braez, the Hrud are known to take other species such as Humans into their tribes where they were given the role of a "zanhaad" that were a sort of slave-cum-pet.[1b] The secretive nature of the Hrud meant that many knew of their existence but little else was known about their civilization leading to them being considered an enigma to the Imperium.[1c]
Hrud religion tends to be unusual in the sense that the clarity of their mass-memory means that their legends, if not real, are based on real events. This beliefs hold the view that their race were created by a benevolent pantheon of gods known as the "Slah-haii" or "most ancient" who intended for them to bask in the sun and be fruitful. It is said that this changed when their gods entered into a war against the "Yaam-kheh" or "Mirror Devils" which saw them either slain, crippled or forced to flee. Their legends say that only a single member of their pantheon still exists known as Qah , a god also known as "He Who Lingers". This solitary member of the godhead is said to had recognized the dangers that would fall upon his beloved children and thus changed them into a race of nocturnal scavengers. Around 500,000 years ago, Qah is said to had told the Hrud that he had other great works to attend to and disappeared. However, he said that he would return to reunite at the time of the "Raheed-skeh" which was the appointed time when the tribes would come together for a final battle against the Yaam-kheh. Inquisitor Maturin Ralei noted the similarity in the Hrud pantheon with other xenos species which included a horned hunter, a red-handed figure, a laughing jester and a hammer wielding artisan.[1b]
They are known to be attracted to darkness similar to the Dark Eldar. Inquisitor Oriel stated that they were scavengers and tunnel-dwellers that could be found all over the galaxy but never in large numbers. He, personally, considered the species to be parasites.
Though little was known about this reclusive and dangerous species, it was known that they dwelled only in darkness and possessed strange, warp-based technology that allowed them to walk between worlds. This even allowed them to corrupt the flow of time with their simple presence. This mysterious nocturnal species were also the creators of Hrud fusils that were a warp-plasma based weapon. Fusils remain one of the few scant artifacts of the Hrud that occassionaly come up for sale in the Imperium and were also in high demand. In functionality, they worked as a form of "plasma musket" that uses an unfathomable mechanism to phase a plasma bolt between realspace and the warp. Thus, any shot from a Hrud fussil bypassed the defenses of the target though they were unpredictable. Despite this being the case, they are favoured by assassins and even Inquisitorial agents. Those weapons that find themselves on the black market are modified to accept Imperial plasma cells though if the mechanism itself is badly damaged then it cannot be repaired by human hands. According to Inquisitor Kryptman, Hrud fusils are a simple symbiosis between melta and plasma technology that are able to fire columns of fire hotter than a star when the mechanism was activated.
They also possess the ability to bottle their Ssaak and even barter it with other races.
The Hrud first appeared as a simple illustration of a 'Nocturnal Warrior of Hrud' in the diagram "other dangerous aliens", along with early versions of a Kroot warrior, Necron, Tarellian dog soldier and other minor species, in the 3rd Edition Rulebook.
The Skaven are humanoid rat creatures from Games Workshop's fantasy counterpart game to 40k, Warhammer. Both races have a similar unkempt, crouched appearance, scavenger culture, and both are depicted as having rat-like tails; both utilize warp-plasma based technology, which appears archaic but is technologically superior to other, contemporary engineering - the Hrud rifle is a "fusil" while the Skaven rifle is a jezail (a musket) - and finally both seem to have similar social habits being described as living in warrens or similar underground tunnel systems.
It could be presumed that the Hrud were originally meant to be Warhammer 40,000 counterparts to the Skaven. With the exception of the Skaven, most Warhammer fantasy races have a counterpart in Warhammer 40,000. Incidentally, early Warhammer 40,000 rules included a toxin called rodotoxin which was effective against Skaven. However, Games Workshop have never stated that the Hrud and the Skaven are parallel races, and supposedly GW wants to move Warhammer 40,000 away from its origins as "Warhammer in space."
It should be pointed out at this stage, that the reader should be cautious when regarding information given to them about the Hrud unless referenced to official material that forms part of the official 40K universe. Because of the similarities between the Hrud and the very popular Skaven, fans have generated much of their own material.
- 1: Xenology
- 2: Kill Team (Novel), [Needs Citation], pg. 194
- 3: Warriors of Ultramar (Novel), by Graham McNeill, Chapters 1, 14, 16
- 4: Warhammer 40,000 3rd Edition Rulebook, pg. 116
- 5: Codex: Chaos Space Marines (3rd Edition, 2nd Codex)
- 6: Inquisitor Rulebook, available for download here, pg. 64
- 7: Warhammer 40,000: Compendium, pg. 153
- 8: Planetstrike, pg. 54
- 9: Index Astartes I
- 10: Codex: Imperial Guard (3rd Edition, 2nd Codex)
- 11: Thorian Faction Sourcebook (Saved archive page, dated July 2013, last accessed 9 September 2015), pg. 26
- 12: Codex: Grey Knights (5th Edition), pg. 47
- 13: Codex: Eldar (4th Edition), pg. 50
- 14: Imperial Armour Volume Two - Space Marines and Forces of the Inquisition, pgs. 30, 138, 150, 160
- 15: GW Spain (accessed 2007.03.11)
- 16: Dark Heresy: Disciples of the Dark Gods, pg. 74
- 17: Elucidium (Short Story) by Simon Spurrier
- 18: White Dwarf 311 (UK), pg. 62
- 19: The Bleeding Chalice (Novel) by Ben Counter, [Needs Citation]
- 20: Warhammer 40,000 6th Edition Rulebook, pg. 170
- 21: Codex: Dark Angels (6th Edition), pg. 23
- 22: Index Xenos Cruelty and Death: The Piratical Kabals of the Eldar (White Dwarf 311 (UK), pp. 62–66)
- 23: White Dwarf 49 (2015) - Codex:Apocryfa Extra - The Hrud Rising
- 24: Imperial Armour Volume Two - Second Edition, pg. 21
- 25: Imperial Armour Volume Ten - The Badab War - Part Two, pgs. 135-136
- 26: Fabius Bile: Primogenitor (Novel), Part One, Chapter Eight.