"We must scour them from the stars before they do the same to us."
A Hive Fleet is a large armada of living, biomechanical starships created by the Tyranids for the purpose of gathering the raw materials and biomass necessary for the reproduction, evolution and expansion of their species. A hive fleet is used to attack and strip star systems of their biomass using the full range of Tyranid bioforms.
Only three primary Tyranid hive fleets and a host of smaller splinter fleets have ever come into direct contact with the Imperium of Man, but they have all brought devastating damage and loss of life.
The Imperium's Segmentum Ultima Command designated them as: Hive Fleet Behemoth, Hive Fleet Kraken and Hive Fleet Leviathan, and they each made first contact with Imperial space in the Eastern Fringes of the galaxy, in the Segmentum Ultima.
Hive Fleet Behemoth arrived in the Milky Way Galaxy in 745.M41, Hive Fleet Kraken in 993.M41 and Hive Fleet Leviathan in 997.M41. Each hive fleet is ultimately governed by the collective psychic Hive Mind of the Tyranid species, though at the heart of any hive fleet are the Norn-Queens who interpret the will of the Hive Mind for other Tyranid organisms and who personally birth almost every Tyranid biomorph present in the fleet, save for its Hive Ships.
The potent psychic power of every hive fleet's connection to the Hive Mind produces an effect known as the "Shadow in the Warp" that prevents travel or communication through the Immaterium in the astrographic vicinity of the hive fleet.
The Tyranids are unlike any other intelligent species to be encountered by humanity since Mankind first reached the stars. They are the ultimate predators, and all living things, from the lowliest insect to the most advanced civilisation, are nothing but their prey. Only now are the inhabitants of the galaxy realising the true scale of the threat; unless the Tyranids can be stopped, it will mean nothing less than the extinction of all life in the galaxy.
The Tyranids are likened to a galactic swarm consuming everything in its path, feeding on entire worlds and leaving only dead husks in their wake. Their threat is such that an unprotected planet can be infested and stripped clean of all its organic material in a matter of weeks without even slowing down the greater advance of the hive fleet.
The Tyranids are a spaceborne species that have inveigled their way into the realms of Humanity, as well as those of other xenos, like a disease spreading through a healthy body. The Tyranids travel in great fleets of gigantic living creatures that serve as spacecraft, each of which is home to countless lesser Tyranid organisms grown in the bubbling organ-sacs of the vessel's reproductive chambers. All of these creatures are born to serve the single entity that is the ship, and the ship itself exists only as part of the entity that is the hive fleet.
When a hive fleet encounters a prey world, it does not invade for territorial gain or out of a sense of pride or vengeance. Indeed, it is doubtful the Tyranids even comprehend such alien concepts. Rather, they invade to harvest valuable biomass and feed their insatiable hunger. The Tyranids require an endless supply of food, not only to nourish the hive fleets, but to grow new Tyranid organisms.
Therefore, when a hive fleet invades a planet rich in life, every action of every Tyranid creature is honed to a single goal -- the total and rapid absorption of that world's population, ecosystems and bio-resources. To this end, the hive fleet creates an army with the express purpose of overcoming the prey world’s defenders before the planet is stripped of every scrap of biomatter and devoured.
The Hive Mind
The Magi Biologis of the Imperium categorise each Tyranid hive fleet as a separate force, an individual entity that competes with other hive fleets for resources. Indeed, each is self-sufficient, appearing to exhibit different strategies and developing unique creatures to overcome its prey. However, the truth is more complex, for each hive fleet is but a splinter of one greater assemblage.
The Tyranids' numbers are vast beyond counting, swarms so large that they block out the very stars, yet each and every creature is but a single cell in the living body of a single super-organism. Every thought and action, every spark of life in the Tyranid race, is bound and interlinked into a single unfathomable consciousness, a great entity that stretches across hundreds of light years of space. This gestalt sentience is known as the Hive Mind.
It holds all Tyranids in a psychic bond that enables them to act together in perfect unison. Under the influence of this ancient, disembodied consciousness, the Tyranids have fed on countless planets and devoured civilisations since time immemorial.
The Shadow in the Warp
The coming of a Tyranid hive fleet is preceded by a smothering psychic signal that envelops entire star systems and disrupts all forms of Warp travel and communication. Swallowed up by psychic-static, whole worlds suddenly go deathly silent, giving no clues as to what is unfolding on the surface below, or of what terrors are about to befall them.
This is the "Shadow in the Warp," and it heralds imminent invasion and horror. It is unknown if the Shadow in the Warp is created deliberately by the hive fleets, or if it is simply a by-product of the Hive Mind's innate synaptic control over its myriad bioforms.
In any case, the Shadow in the Warp creates fear and panic wherever it falls, instilling a pervasive dread into the minds of a prey world's defenders, plunging entire planets into misery and despair. For highly-psychic races, such as the Eldar, or for luckless psykers caught within this enervating effect, the malaise is magnified tenfold.
Should a psyker attempt to use his otherworldly abilities, the cerebral cacophony worsens even further; the psychic sound of a billion alien thoughts scratch at his mind, and unless he is particularly strong-willed he will be pitched into an insanity where he will repeatedly utter phrases in a tongue too alien to properly pronounce.
For intelligent species such as the humans of the Imperium of Man, whose means of interstellar communication and travel rely upon highly specialised psykers such as Astropaths and Navigators, the Shadow in the Warp is one of the deadliest facets of the Tyranid menace. Bereft of their means to call for reinforcements or safely navigate the surrounding space, the worlds of the Imperium are easily isolated from the wider galaxy.
This means that, by the time the Shadow in the Warp falls, it is already too late; these beleaguered planets are effectively on their own. They must fend for themselves and face the Tyranid swarm with the weapons they have at hand, or die in the attempt.
"We cannot live through this. Mankind cannot live through this. In a single day, they have covered this planet with a flood of living blades and needle-fanged mouths. Kill one, and ten take its place. If they are truly without number, then our race is doomed to a violent death before every shred of our civilisation is scoured away by a force more voracious than the fires of hell themselves. Death! By the Machine God, Death is here!"
- — Magos Varnak, last words
Mankind's first recorded contact with the Tyranids happened in early 745.M41, on the eastern outskirts of the Imperium. Up to this point, Mankind was wholly unaware of the new threat on its borders, and if any of the galaxy's older empires knew of the oncoming swarm, they did not see fit to warn the upstart Imperium. For solar decades, since their arrival on the galactic rim, the hive fleets had consumed worlds with no intelligent life, replenishing the reserves of biomatter expended during the long, slow crawl through the intergalactic void.
Now reinvigorated, the aliens descended upon the far-flung Imperial Ocean World of Tyran Primus -- an invasion for which the Imperium would thereafter name their species: Tyranids. During the subsequent invasion, the Imperial forces were decimated, the planet's defences swiftly overcome by the vast invading Tyranid horde.
Unable to transmit a message by means of astrotelepathy, the aliens' Shadow in the Warp having cut off all psychic communication, Magos Varnak, the commander of the Adeptus Mechanicus Explorator base on the world, compiled a data-codex containing Tyran's records. With only seconds left, Varnak hid the codex in a bore shaft in the depths of the Mechanicus outpost, some 3,000 metres below the planet's surface, hoping that it would be recovered later by the Imperium.
The courageous Tech-priest then activated the sacred self-destruct Rune of Ending, annihilating the entire outpost in a cataclysmic plasma explosion. Tyran Primus was lost. The First Tyrannic War had begun.
"An alien threat has risen from beyond the abyss, a swarm so vast that it blots out the stars. This horror fights neither for power nor territory, but rather to feed a hunger so insatiable that it will eventually devour the entire galaxy."
Having scoured Tyran Primus of biomass, the alien hive fleet moved on in search of other worlds to feed upon, pushing its tendrils ever deeper into the galaxy whilst the death screams of an entire world went unheard. Were it not for a single man -- Inquisitor Kryptman -- the fate of Tyran might have gone entirely unnoticed.
After all, the galaxy is a big place, mysteries are commonplace and the Imperium is as slow to react as only a monolithic bureaucracy can be. Whilst in time many other Inquisitors, including such distinguished names as Bronislaw Czevak, Agmar and Solomon Lok, would come to realise the true threat of the Hive Mind, were it not for Kryptman, its very existence would not have been known before it was already too late. Indeed, whether through a quirk of fate or out of some investigative instinct, Kryptman's decision to personally investigate Tyran's mysterious silence proved vital to the Imperium's survival.
By the time Kryptman reached Tyran, a standard year had passed since the attack. At first, the Inquisitor could not equate the husk of a planet he found to ocean-bound Tyran Primus. The world had been sucked dry; every scrap of vegetation and every drop of water was gone. A crater was all that remained of the Adeptus Mechanicus outpost, and all that could be found of the planet's Imperial Navy cruiser fleet were acid-eaten hulks; icy shells devoid of life and adrift in space.
After a long search, Inquisitor Kryptman recovered Magos Varnak's data-codex, the knowledge contained within it bought with the life of an entire planet. What Kryptman saw when he reviewed the fragmented data was a dire prophesy of doom; static-laced images of scythe-limbed aliens, footage of the skies over Tyran turning black with swarming monsters, and orbital pict-views of a fleet of living voidships so vast that the stellar horizon was veiled in inky blackness.
Kryptman felt hollow as he realised what he had discovered. Not wasting another moment, the Inquisitor set forth to warn the galaxy of the oncoming horror from beyond the stars, a horror he named "Tyranids" after the doomed world they had consumed.
Unfortunately for the Imperium and the other intelligent races of the galaxy, it is not only Hive Fleet Leviathan that is assailing the galaxy. New hive fleets are even now beginning to emerge from their cold sleep through the intergalactic void. Hive Fleet Medusa, mistakenly thought by the Imperium to be another tendril of Leviathan, was last recorded feasting upon the Ice World of Shadrac.
Hive Fleet Moloch's inexorable advance from the galactic north is also gathering momentum as it devoured the Kiltor Sector and now the Tarellian civilisation. Perhaps most worrying of all are Hive Fleets Scylla and Charybdis carving parallel paths up through the Segmentum Pacificus and Segmentum Solar, the closest known Tyranid threat to Terra itself. Though the Imperium might have a little time left to prepare its defences against these twin threats, the Eldar Saim-Hann Craftworld is caught in the jaws of these two Hive Fleets, and cannot easily navigate a path to avoid one without risking falling into the clutches of the other.
None know for sure how many other hive fleets still lie dormant within the void beyond the rim of the Milky Way, slowly approaching our galaxy to wake and feed. Nor are the threats of previous Tyranid invasions truly over. The splintered fleets of Hive Fleet Kraken are regaining their strength as they feast on a bounty of worlds ill-prepared to defend themselves whilst the galaxy looks to supposedly greater threats. Long dormant remnants of Hive Fleet Jormungandr stir to life, bringing several Imperial worlds to the brink of destruction.
Rumours even abound that remnants of Hive Fleet Behemoth, thought slain over two standard centuries ago, continue to ravage populations and settlements within the Ultima Segmentum, with scattered reports of Tyranid attacks on worlds from Calth to Macragge and beyond. With so many threats emerging from unseen quarters, many Imperial worlds are holding back from reinforcing the on-going fight against Hive Fleet Leviathan, choosing to preserve their forces for wars against the Great Devourer closer to home.
A Glimmer of Hope
"Tyranids are creatures from our darkest nightmares. But remember this; they can bleed and they can die..."However, as the ongoing Octarian War is proving, the Tyranids are encountering ever-greater levels of resistance from their prey. Whilst the Imperium reinforces whole star systems, raising thousands of Astra Militarum regiments and dozens of Space Marine Chapters solely to combat the Tyranid threat, several Aeldari Craftworlds have begun to burn entire worlds to cinder, employing ancient and highly advanced weapons of destruction not used in millennia.
The T'au Empire, having learned well at the claws of Hive Fleet Gorgon, are developing new technologies and weaponry to fight the Tyranids and field-testing experimental prototypes to defend their realm. Even the Necrons and the forces of Chaos are turning their attentions towards a foe that is slowly devouring a galaxy that both believe is theirs alone to rule over or despoil as they see fit.
So far these efforts are, at best, succeeding in slowing the Leviathan's rapacious advance, but it is only a matter of time before the Hive Mind adapts. With every lost battle, the hive fleets create new breeds of warrior-organisms and bio-constructs to counter and defeat their foes. Yet with every victory, another world dies, devoured to feed the insatiable hunger of the Hive Mind.
Primary Hive Fleets
- Hive Fleet Behemoth - Hive Fleet Behemoth was the first major Tyranid hive fleet encountered and defeated by the Imperium of Man. The ensuing conflict became known as the First Tyrannic War. This hive fleet was eventually destroyed in 745.M41 by the combined might of the Ultramarines, the White Scars, and the Imperial Navy.
- Hive Fleet Kraken - Hive Fleet Kraken was the second major Tyranid hive fleet to invade the galaxy. It was responsible for the outbreak of the Second Tyrannic War, which began officially in 992.M41 and ended only after the Ultramarines Chapter of Space Marines successfully broke the back of the Tyranid invasion in Imperial space at the Battle of Ichar IV and the Eldar of Craftworld Iyanden successfully defended their home, at great cost, against the Tyranid horde.
- Hive Fleet Leviathan - Hive Fleet Leviathan was the third and largest Tyranid incursion into the Milky Way Galaxy in 997.M41 and marked the start of the ongoing Third Tyrannic War for the survival of the Imperium of Man. Less than five standard years after the defeat of the Hive Fleet Kraken in the Second Tyrannic War, Lord Inquisitor Kryptman noted the tell-tale signs of yet another Tyranid invasion in 997.M41. He implemented the Kryptman Census, burning out dozens of Astropaths in the attempt to contact scores of worlds on every fringe of the Imperium. Slowly, the responses -- and lack of them -- formed a pattern, and the venerable Inquisitor was able to chart the course of the Tyranids' latest hive fleet to arrive in the galaxy. Codenamed "Leviathan", this time the Tyranids approached from below the galactic plane, attacking from two points spaced wide apart in the shape of a closing pair of jaws, cutting off large portions of the galaxy from Warp travel or astropathic communication. At a great cost in human life, a combined force of Planetary Defence Force troops, two regiments of the Imperial Guard, the Ultramarines and Mortifactors Chapters of Astartes, and a Deathwatch Kill-team under the command of Inquisitor Kryptman crushed the left "half" of the Leviathan on the world of Tarsis Ultra, destroying the Tyranids nearest to Terra, and reestablishing astropathic contact with the Imperial worlds between Leviathan's jaws. The Imperium had won its first victory in a war that had only begun.
Other Hive Fleets
There are many other hive fleets known to exist in the galaxy or to be approaching it from the vast void of intergalactic space.
Several of these hive fleets are splinter fleets of the original three to invade the galaxy and include the following:
- Hive Fleet Ouroboris - When Miriamulus the Elder, the then-cardinal of Thracian Primaris recorded the history of the "Legion of Ouroboris" in the 36th Millennium, this account detailed attacks in the Helican Sector in an earlier age, thousands of standard years before. The legion was described as consisting of "winged monsters" that descended from the heavens and stripped the countryside of all life, "vomited from the bellies of great beasts which clouded the stars with their numbers." An analysis of the Warlord-class Titan Mechanica Cranus, a cited veteran of the Ouroboris Wars, revealed distinctive bio-plasma scarring and pyro-acid burns now known to be consistent with the damage caused by Tyranid biomechanical weapons. It is believed the Space Wolves Space Marine Chapter also possesses trophies of Tyranid-like bioforms dating from this epoch, including the so-called "Kraken's Egg." The cardinal attributed the Emperor Himself with leading a crusade that caused the Beasts of Ouroboris to fall upon themselves, culminating in a mighty twelve-day-long battle over a Warp rift dangerously close to the Eye of Terror. However, augur-dating techniques place the battle damage sustained by Mechanica Cranus as occurring post-Heresy, making the Emperor's embodied presence extremely unlikely. It is theorised that Hive Fleet Ouroboris may have consisted of some Tyranids who were drawn ahead of the other fleets by treacherous Warp currents and deposited at the Eye of Terror in the Milky Way. This theory could also explain the presence of Tyranid splinter fleets in Segmentums other than the Segmentum Tempestus.
- Hive Fleet Tiamet - First encountered in the large double binary system on the Eastern Fringe known as the Tiamet System, it is theorised by Imperial xenologists that this hive fleet was a Tyranid implant-probe, possibly molecular-coded DNA, sent ahead (perhaps hidden within cosmic debris or solar winds) to seed the star system and spread of its own accord ahead of the arrival of much larger hive fleets. This system was discovered by an Imperial Explorator fleet hailing from Triplex Phall in the 35th Millennium. The Tiamet System contained seven life-sustaining worlds and a host of lesser planetoids. The Explorator fleet discovered to their cost that every biosphere in the system was a Death World of the most voracious kind. Xenologists eventually determined that the life all over the system shared a common genetic ancestry and had developed various ways to get from world to world to seed new territory. Realising their own craft could be contaminated from entering the system, the Explorators quarantined themselves in Tiamet rather than infect the wider Imperium. They were to survive and report for another one hundred and sixty-two solar hours before succumbing to the lethal denizens of the fecund realm. The Tiamet System's worlds were systematically fusion-bombed on several occasions but life was never extinguished there; it now lies within the area swept over by Hive Fleet Kraken and as such its fate is unknown.
- Hive Fleet Collossus - Several large nomadic fleets of curious, conch-like spacecraft apparently grown from natural stone were sighted through the Segmentums Tempestus and Ultima late in the 38th Millennium, bearing many similarities to hive fleets. The centauroid bio creatures aboard them (which may have been members of the species recorded in Imperial archives as Zoats) were known to communicate, albeit telepathically, with other races -- unlike any other Tyranid organism before or since. The denizens of Colossus claimed to be slaves escaping their oppressors, but their frequent contacts with other alien races and attempts to settle in Imperium space caused them to be declared Xenos Horribilis early in the 39th Millennium. The xenocidal fifty-year-long Zorastra-Attila Wars followed as the entire race hurled itself against humanity with terrifying ferocity, revealing their true, murderous nature. The last known Collossus vessel was eventually destroyed in 226.M39 above the world of Zorastra. The impact of its shattered remains rendered the northern hemisphere of that world uninhabitable until late in the 41st Millennium. Only now are Adeptus Mechanicus Explorator expeditions beginning to piece together the truth. Due to inconsistent records, Imperial scholars cannot agree as to whether Collossus was wiped out during this campaign or during the Helican Crusade. Indeed, it is known that in 897.M41, elements of what has now been identified as Hive Fleet Collossus invaded the Imperial Civilised World of Thressiax. Imperial forces on the planet were unable to stop the constant influx of invaders and Imperial High Command issued a ruling for all forces to withdraw so that the Imperial Navy could conduct an Exterminatus action from space, and in the process leave the settlers of Thressiax to their fate. However, the Space Wolves Chapter's Wolf Lord Bran Redmaw, resupplying his Great Company upon Thressiax at the time, objected fiercely to the command. He sent two full squads of Grey Hunters to reinforce the spaceport of Montberg and give the Imperial settlers a chance to evacuate. At the spaceport, the Grey Hunters set about training the settlers in anti-Tyranid tactics. When the forces of Colossus attacked, these ad hoc troops managed to hold the walls of the spaceport long enough for the settler families to escape off-planet safely. Six Grey Hunters survived and the Imperial High Command ordered them to be stripped of all Astartes honours for disobeying a direct command, but Bran Redmaw instead promoted all of them into his personal Wolf Guard.
- Hive Fleet Naga - Hive Fleet Naga was a relatively small hive fleet that invaded the galaxy from the Eastern Fringe somewhere to the galactic north of the T'au Empire in 801.M41, destroying countless xenos domains and devouring several Aeldari worlds. The Aeldari referred to this hive fleet as Shai'naid, the "Endlessly Winding Serpent," and only through the combined efforts of Aeldari fleets from Idharae, Iyanden and Malan'tai Craftworlds, was Hive Fleet Naga destroyed in 812.M41. Unfortunately, the Tyranid Hive Mind absorbed several dozen samples of new biomass, including the DNA of the Aeldari, gaining valuable experience of Aeldari military strategies and capabilities.
- Hive Fleet Dagon - Hive Fleet Dagon, believed to be a splinter fleet of Hive Fleet Behemoth, was the first major Tyranid incursion into the Jericho Reach region of the Ultima Segmentum. The Shadow in the Warp cast by the Tyranid Hive Mind within this volatile region of space first heralded the arrival of this new and terrible hive fleet in 812.M41. Communication between parts of the Achilus Crusade and the reconquered regions of the Jericho Reach was lost without warning. Particularly affected was the Orpheus Salient of the Achilus Crusade that was lost to communication and access with the rest of the Reach behind the hive fleet's crawling Shadow of Warp interference. In 814.M41, the Deathwatch warship Thunder's Word entered the Freya System to investigate the silence of an astropathic relay. It found no trace of the relay and indeed no trace of any life in the Freya System. Preparing to leave the star system, the Thunder's Word encountered two Tyranid drone ships. Its hull scored and pitted with acid and its magazines nearly exhausted, the Thunder's Word arrived at Watch Fortress Erioch bringing news that the Tyranids had come to the Jericho Reach.
- Hive Fleet Gorgon - The Gorgon was a splinter fleet of Hive Fleet Behemoth that invaded the space of the T'au Empire in 899.M41, it represented the T'au's first horrific encounter with the Tyranids; the hive fleet was destroyed in 903.M41, through the combined efforts of the T'au Fire Caste and the Imperial Guard. Regions of the T'au Empire that have been left barren by the rampaging hive fleet are known as the "Zone of Silence."
- Hive Fleet Kronos - Where Hive Fleet Kronos travels, the Shadow in the Warp is at its most suffocatingly powerful. So strong is the psychic connection between Kronos and the Hive Mind, that a stifling aura of null power drifts ahead of its invasion swarms, agonising psychically active foes and draining their spirit energy to bolster its own hosts. Even as this phenomena throws the enemy into fearful confusion, thousands upon thousands of warrior-forms advance, unleashing a storm of organic missiles; Kronos avoids engaging its prey at close range when possible, for the prey it hunts revels in brutal close-quarters fighting, and thus a ranged kill is a more efficient method of extermination.
- Hive Fleet Scarabus - Hive Fleet Scarabus was annihilated by the troops of the 9th Cadian Shock Troopers Regiment at the walls of Fortress Carcasson in 937.M41. The 9th Cadian did not lose even a single company of troops in this conflict.
- Hive Fleet Locust - In 945.M41, this hive fleet largely wiped out the population of the Imperial world of Ulmore before the arrival of the Ultramarines Space Marine Chapter in which the valiant Sons of Guilliman managed to drive back the hordes of the Great Devourer during the subsequent Battle of Ulmore.
- Hive Fleet Lotan - Vectoriums of the Death Guard's 4th and 7th Plague Companies engage the Tyranids of Hive Fleet Lotan amidst the steaming jungles of Hesp. When the swarms deploy Toxicrenes and Venomthropes to poison the environment, the Death Guard respond with plague spells, Virus Bombs and daemonic diseases. With neither side willing to back down, the atmosphere of Hesp becomes ever more toxic until the jungles, and even the warring armies, are reduced to a gory, bubbling soup. The first Tyranid Hive Ship to taste this poisoned slurry recoils, its proboscis melting, and is bombarded into oblivion by the rest of its fleet. The Jungle World of Hesp is left as an endless sea of toxic slime, too virulent for even the Hive Fleets to devour.
- Hive Fleet Perseus - This Tyranid hive fleet battled the Ultramarines Space Marine Chapter in 976.M41, but in 982.M41, it subsequently drifted out of Imperial-held space and disappeared. Its current location and activities are unknown.
- Hive Fleet Magalodon - Originally one of the splinter fleets that formed following the defeat of Hive Fleet Kraken in 992.M41, Magalodon has since grown exponentially to be classified by the Imperium as a distinctive hive fleet of its own, which continues to ravage Imperial space.
- Hive Fleet Jormungandr - A small Tyranid hive fleet that entered the Imperium from the North East of the Ultima Segmentum in 993.M41, Jormungandr quickly gathered large quantities of biomass by preying on unprotected worlds. Within two standard years of the first recorded attack, Jormungadr had effectively sealed off the entire Thalassi Sector. The hive fleet's vanguard was wiped out by Commander Chenkov leading over a million Imperial Guardsmen of the Valhallan Ice Warriors' 18th "Tundra Wolves" Regiment. When a portion of the Crimson Castellans Chapter was corrupted by Chaos and turned Renegade, becoming a piratical warband of Chaos Space Marines, the Loyalist Castellans hunted down their corrupted brethren on the Hive World of Sephrax. But while they were engaged in battle, the Tyranid Hive Fleet Jormungandr unexpectedly descended upon the world and forced both sides to lay down their animosity to defend themselves against the swarms of bloodthirsty Tyranids that threatened to destroy the world and both groups of Astartes. However, the hive fleet's sheer numbers soon overwhelmed all the combatants. The Crimson Castellans' Chapter Master Sojai Antiro died in the bowels of the underhive of Hoventa Hive alongside his 1st Company Veterans, growling his defiance with his last breath even as Tyranid Raveners encircled him and tore him to bloody shreds. The Renegade Crimson Castellans' leader, the pirate and self-styled "Arch-Commodore" Bloodspite, fled with the remainder of his forces to the lair he had established in an asteroid in orbit of Sephrax. But the asteroid and its defenders were ultimately swallowed by a Hive Ship of truly enormous size. The Crimson Castellans' Chapter homeworld of Vorl Secundus was abandoned shortly thereafter, and it is unknown whether any elements of the Chapter, Loyalist or Renegade, have survived the fury of Jormungandr.
- Hive Fleet Medusa - This minor hive fleet invaded the galaxy from the galactic northeast through the region of the Ghoul Stars and close to the path of Hive Fleet Moloch in 997.M41. In 998.M41, Hive Fleet Medusa, mistakenly thought by the Imperium to be another tendril of Hive Fleet Leviathan, invaded the isolated Ice World of Shadrac. The Space Marines of the Space Wolves Chapter fought side-by-side with the battered survivors of the 10th Slovak Imperial Guard garrison, enacting a heavy toll in alien dead before they were forced to flee the planet.
- Hive Fleet Pythos - The Red Talons Chapter held the Fortress World of Orask on the edge of the Ghoul Stars from an invading splinter of Hive Fleet Pythos.
- Hive Fleet Moloch - Hive Fleet Moloch was a minor hive fleet that plunged through the Ghoul Stars into the galactic north of the known galaxy in 998.M41. A vanguard tendril first threatened the Agri-World of Jollov in 932.M41 just as Techno Magus Stannum Vir discovered fragments of a lost Standard Template Construct (STC) data core on the planet. The world's spaceport was defended by Imperial Guard regiments comprised of Agathon, Catachan Jungle Fighters, Kanak, Molov, and Mordian Iron Guard regiments, selling themselves dearly, which bought enough time for the Adeptus Mechanicus to flee with their precious STC discovery. Much later, the 9th Vostroyan Firstborn Regiment, "The Old Irascibles" met their ultimate fate during the Fall of Karak Prime in 998.M41 at the hand of Moloch. They held the main hive city for 18 solar months against the brutal onslaught of a splinter fleet of Hive Fleet Moloch, valiantly facing a Tyranid swarm that stretched from the base of the city's walls to the distant horizon. With the onset of midwinter, and with the rapid depletion of ammunition and supplies, the 9th Vostroyan knew that they were doomed and vowed to sell their lives dearly. Only when the bulk of the Tyranid swarm had passed into the city did the regiment detonate its nucleonic stack, incinerating the hive city, its defenders and an estimated 85% of the Tyranid swarm. With the coming of midwinter, the few surviving Tyranid organisms eventually starved to death and the splinter fleet was entirely defeated.
- Hive Fleet Ophidia - First encountered in 998.M41, Hive Fleet Ophidia has apparently been mostly destroyed, though splinter fleets and remnants still remain active in the southern regions of the Ultima Segmentum.
- Hive Fleet Hydra - This dormant hive fleet was recently discovered in 999.M41 by the Drukhari of the Poisoned Fang Kabal on the very extremes of the galaxy's eastern spiral arm. Instead of destroying the vulnerable hive fleet, the Dark Eldar boarded the largest Hive vessels, intent on bringing new specimens back to their Kabal's Haemonculi. However, the Drukhari were unprepared for the rate at which the bio-ships awoke from their aeons-long hibernation, and every Aeldari pirate that set foot inside one of the living ships was slain, butchered by a frenzied tide of Tyranids spawned to protect the living vessel. The remaining Drukhari fleet attempted to escape, but for every drone ship they destroyed, two more took its place. Prematurely awakened from its slumber, Hive Fleet Hydra accelerated its advance into the galaxy to slake its hunger.
- Hive Fleet Charybidis and Hive Fleet Scylla - Hive Fleets Chraybdis and Scylla are separate Hive Fleets that are both carving parallel paths through the Segmentum Pacificus, the closest known Tyranid threat to Terra. Additionally, unless the Saim-Hann Eldar Craftworld alters its course, it will fall into the clutches of the twin hive fleets.
- Hive Fleet Eumenides - Sometime during the late 41st Millennium, this Tyranid hive fleet battled against Hunter Cadres of the T'au Empire led by Commander Shadowsun. Then, in 990.M41, the planet Kitab in the Keplar System came under attack by a splinter of Hive Fleet Eumenides. The Raven's Watch Chapter was the first to respond to the distress calls, with the Stormtalon, the Talon of Johannes, the first craft to breach the planet's atmosphere. Having deployed the Ironclad Dreadnought Brother Crissica, the Stormtalon streaked across the desert sands towards the invasion fleet's primary synapse node. The craft's pilot was able to deploy Terminator Squad Foran and destroy the node before being forced to leave combat airspace by flocks of ravening Harpies and clusters of Mucolid Spores.
- Hive Fleet Chimera - One of many new hive fleets that currently assails the known galaxy. Like numerous other Tyranid fleets, Hive Fleet Chimera was first thought to be a splintered tendril of Hive Fleet Behemoth and not a separate hive fleet in its own right.
- Hive Fleet Grendel - One of many new hive fleets that have recently emerged from their cold sleep through the inter-galactic void, Hive Fleet Grendel currently assails the known galaxy.
- Hive Fleet Harbinger - The Harbinger is a recently discovered hive fleet that currently assaults the territory of the Imperium. A splinter fleet of Hive Fleet Harbinger recently consumed the Imperial Forge World of Arcetri.
- Hive Fleet Proteus - Hive Fleet Proteus is a Tyranid splinter fleet discovered in the Segmentum Tempestus by the Imperial Fists Chapter. Proteus was making its way down the galactic plane towards Terra by way of the Inwit Cluster.
The scattered remnants of the great attack by Hive Fleet Kraken on Ichar IV fled towards the galactic core, eventually driving within the Imperial defensive perimeters that had been erected to contain the Kraken. These so-called "splinter fleets" have, if anything, become an even greater threat as they feed upon unsuspecting and ill-defended worlds far from the major war zones.
Running battles with the splinter fleets have continued for many years since Hive Fleet Kraken's passage, draining the galaxy's defences against later incursions. It is doubtful if the true extent of the devastation caused by the hive fleet will ever be known.
Splinter fleets can comprise as few as a dozen Hive Ships, but even a dozen bioships are more than capable of overrunning a world and harvesting its biomass to become a yet greater threat. Some have become so large as to be classified as a new, distinct hive fleet. Indeed, Hive Fleet Magalodon grew from one of Kraken's sundered tendrils, and continues to ravage the Imperium to this day.
There is no doubt that by this point the Tyranid Hive Mind has learned a great deal about the galaxy's defences from the actions of these splinter fleets. Every battle that a group of Tyranids engages in, whether they are victorious or not, only adds to the Hive Mind's growing depth of knowledge about its prey within the Milky Way Galaxy.
Some Imperial savants of a particularly melancholic turn of mind believe that gaining this information was the true goal of Hive Fleet Kraken's invasion. It is perhaps preferable to believe that the Hive Mind has planned this outcome in advance, than to believe that it has the strategic skill to turn even its greatest defeats into longer-term victories.
- Codex: Blood Angels (5th Edition), pg. 17
- Codex: Eldar (4th Edition), pp. 52-53
- Codex Heretic Astartes - Death Guard (8th Edition), "The Doom of Hesp," pg. 23
- Codex: Imperial Guard (5th Edition), pp. 18, 23-24, 27
- Codex: Orks (4th Edition), pg. 29
- Codex: Space Marines (5th Edition), pp. 30-33, 40
- Codex: Space Wolves (5th Edition), pp. 19, 21
- Codex: Tau Empire (6th Edition), pg. 35
- Codex: Tyranids (8th Edition), pg. 37
- Codex: Tyranids (6th Edition), pp. 8-12, 14-24, 26-29, 32-47, 49-56, 62, 64, 71-75, 77-80
- Codex: Tyranids (5th Edition), pp. 8-15, 16-21, 23-25, 28-31, 38, 59, 66
- Codex: Tyranids (4th Edition), pp. 6-8, 24-25, 59
- Deathwatch: Core Rulebook (RPG), pp. 341-342
- Deathwatch: Mark of the Xenos (RPG), pp. 33-34
- Deathwatch: Know No Fear (RPG), pg. 11
- Deathwatch: The Jericho Reach (RPG), pp. 170-176
- Iyanden: A Codex: Eldar Supplement (Digital Edition), pp. 45-47
- Warhammer 40,000: Planetstrike (Supplement), pg. 30, 54, 57-59, 74-77
- Warhammer 40,000: Rulebook (6th Edition), pg. 175
- Warhammer 40,000: Rulebook (5th Edition), pg. 166
- Warhammer 40,000: Rulebook (4th Edition), pg. 163
- White Dwarf 362 (UK), "Liber Apocalyptica: Trygons", pg. 46
- White Dwarf 97 (UK), "The Ultra-Marines" pp. 40, 45
- White Dwarf Weekly 37 (11 Oct 2014), "The White Dwarf Parade - Ironclad Dreadnought, Brother Crissica", pg. 78
- Lone Wolves (Graphic Novel) by Dan Abnett and Karl Richardson
- Planetkill (Anthology) Edited by Nick Kyme and Lindsey Priestley
- Priest of Mars (Novel) by Graham McNeill
- Legends of the Space Marines (Anthology), "Orphans of the Kraken" by Richard Williams
- Warriors of Ultramar (Novel) by Graham McNeill
- The Dread Sentinels of Dorn (Short Story) by Rob Sanders
- Forgotten Fleets - The Spore of the Alien: Xenos Threats Exposed
- Dawn of War II (PC Game)
- Battlefleet Gothic Armada 2 (PC Game)