The Morlocks were the veteran Space Marine Battle-Brothers of the Iron Hands Legion who served as Primarch Ferrus Manus' personal Honour Guard. These elite Veterans of the Iron Hands' 1st Company were so-named for the fearsome visage they presented like the vengeful predators of the same name that howled across the frozen tundras of their Legion homeworld of Medusa. The Morlocks were all members of the Iron Hands' Clan Company Avernii. The Morlocks were the deadliest and most experienced warriors of the Xth Legion, and whatever force was arrayed against these black-coloured Terminators could not hope to survive their wrath. The Morlocks were the bloody tip of the spear that drove hard into the vitals of the Xth Legion's foes.
As the personal honour guard of Ferrus Manus, the Morlocks often stood sentinel aboard the Primarch's flagship, the Battle Barge Fist of Iron, the mightiest of them protecting the gates of the Primarch's inner sanctum, the Iron Forge, located within the ship's Anvilarium, the large audience chamber where mighty deeds were planned and unbreakable bonds of brotherhood were forged. The Morlocks were led by Gabriel Santor, the Xth Legion's First Captain and Equerry to the Primarch. Santor hailed from the Avernii Clan on Medusa, as did all of the members of the Morlocks.
Shortly after the corruption of the Emperor's Children's Primarch Fulgrim, his IIIrd Legion was ordered by the Warmaster Horus to rendezvous with the Iron Hands' Primarch and attempt to sway Ferrus Manus, Fulgrim's closest friend amongst the Primarchs, towards the cause of the Traitors. The two Primarchs met aboard Ferrus Manus' flagship. Great bonds of friendship and brotherhood had long existed between them, and Fulgrim felt that he could convince Ferrus of the righteousness of Horus' cause. Fulgrim's hope proved disastrously wrong and the meeting of the two Primarchs in Ferrus' private inner sanctum in the Anvilarium did not go well. Ferrus was outraged that his brothers would dare to turn against their father the Emperor.
The meeting ended in violence as The Gorgon made his difference of opinion known to the Phoenician with his weapons. Ferrus was determined to stop Fulgrim's betrayal of the Imperium before it could even begin. Ferrus used his silvery necrodermis hands to attempt to destroy Fulgrim's sword Fireblade, but the resultant explosion knocked him out. Fulgrim intended to kill his brother with his own weapon, the warhammer Forgebreaker, but proved unable to kill his oldest friend despite the promptings of the Slaaneshi daemon that now throttled his soul. Instead he took the Gorgon's beloved warhammer, a reminder of the bond the two Primarchs had once shared. When Fulgrim emerged from Ferrus' inner sanctum, he gave a signal to his Phoenix Guard who instantly, and in perfect synchronicity, beheaded all ten of the Iron Hands Morlocks who served as Ferrus Manus' bodyguard with their Power Halberds. The Emperor's Children's First Captain Julius Kaesoron struck out against his Iron Hands counterpart, Gabriel Santor, and very nearly killing him with his Lightning Claws. Fulgrim successfully fled the Iron Hands' expeditionary fleet in his personal assault craft, the Firebird, when he ordered his flagship, the Battle Barge Pride of the Emperor and its Escorts, to open fire upon the ships of the 52nd Expeditionary Fleet. This surprise attack crippled them and provided a distraction while Fulgrim and the Emperor's Children fled into the Warp to rendezvous with the rest of their 28th Expedition in the Istvaan System.
Things eventually came to a head at the Drop Site Massacre of Istvaan V. Led by First Captain Gabriel Santor, ten full companies of Morlocks hungered to confront the Emperor’s Children and make them pay for the dishonourable murders done to their number in the Anvilarium of the Fist of Iron. The Morlock Terminators, led by The Gorgon, formed the centre of the Loyalists' assault as the Primarch of the Xth Legion sought out his fallen brother Fulgrim. Finally the forces of the Emperor’s Children and the Morlocks came together in a riot of bloodshed and death. The Morlocks' superior armour and experience gave them an advantage over the rank and file Astartes of the Emperor’s Children, but they were greatly outnumbered. While Ferrus Manus and Fulgrim clashed in a final confrontation, the Traitors' revealed their trap, as the second wave of the Loyalist assault, composed of the Alpha Legion, Iron Warriors, Night Lords and Word Bearers, revealed their true allegiance to Chaos. Fulgrim's own honour guard, the Phoenix Guard, answered with a terrible war cry and leapt to meet the Morlocks in a searing clash of blades. Electric fire leapt from the golden edges of the Power Halberds and the Lightning Claws of the warriors, and a storm of light and sound flared from each life and death struggle. Now surrounded on all sides by Traitors after the second wave had revealed their treachery, the Morlocks were circled by the Traitors and in the midst of cries of pain and roaring savage glee, the Morlocks of Ferrus Manus were slain to a man. It is unknown whether the Morlocks were reconstituted by the Iron Hands Chapter after the events of the Horus Heresy.
- Gabriel Santor - Gabriel Santor served as the Equerry to Primarch Ferrus Manus as well as the First Captain of the Iron Hands Legion's elite 1st Company and elite Honour Guard, known as the Morlocks, during the Great Crusade and the opening days of the Horus Heresy. When the Emperor's Children were corrupted by the Warmaster Horus of the Sons of Horus Legion, they attempted to sway their fellow cousins, the Iron Hands, to the Warmaster's cause. Gravely miscalculating Ferrus Manus' response to his offer, the Emperor's Children's Primarch Fulgrim callously attacked his brother, leaving him gravely wounded, as well as having ten of his elite praetorians cut down in a cowardly attack that left Gabriel Santor near death. Enraged by this base betrayal, Ferrus Manus led his Honour Guard in the initial first wave assault during the tragic events of the Drop Site Massacre on Istvaan V. Overextended and cut-off by the Warmaster's treacherous trap, Gabriel Santor was confronted by the Chaos-corrupted Emperor's Children First Captain Julius Kaesoron and was slain by that vile servant of Slaanesh, just as his Primarch Ferrus Manus was slain by his former brother Fulgrim.
- Vermanus Cybus - Vermanus Cybus was the senior surviving Morlock veteran of the Drop Site Massacre on Istvaan V. Gathering with the remnants of the Iron Hands Legion that had fought their way out of the killing grounds of the Urgall Depression on Istvaan V, he joined the ad hoc group of survivors of that battle aboard the Iron Hands Strike Cruiser Sisypheum as it fled the Istvaan System. Cybus possessed multiple chimeric bio-modifications and had been viewed as nearly pathological in his reverence for the machine and his loathing for flesh. In truth, Cybus was a warrior not even his Battle-Brothers could be around for any length of time, for adherence to the doctrines of augmetic superiority had already spread through many of the Battle-Brothers of the Iron Hands Legion even before the death of Ferrus Manus and his warning against such beliefs to the Xth Legion. Before the betrayal at Istvaan, Cybus had fought beside the warriors of the Emperor's Children Legion on numerous occasions. He had always respected the IIIrd legion's devotion to the attainment of perfection, finding much to admire in the Emperor's Children's martial ethos. Many years earlier, Cybus had argued long into the night with a young officer of the IIIrd Legion named Rylanor on the merits of organic strength against augmented power, mocking the Legionary’s faith in his flesh while extolling the virtue of iron. Cybus was an uncompromising man of little personal charisma, but he had a secutor's grasp of the methodology of combat.
- Septus Thoic and Ignatius Numen - This duo of Morlocks veterans were some of the very first Iron Hands warriors to make planetfall on Istvaan V, having marched alongside the best and bravest of the Xth Legion. Gathering with the remnants of the Legion that had fought their way out of the killing ground of the Urgall Depression on Istvaan V, they joined the ad hoc group of survivors of that battle aboard the Iron Hands Strike Cruiser Sisypheum as it fled the Istvaan System. The Iron Hands and their mortal serfs formed the bulk of the survivors to take refuge on that starship, but warriors of the Salamanders and a single Raven Guard Astartes were counted amongst their number as well. The months that followed saw the Sisypheum embark on a series of hit-and-run attacks on Traitor forces on the northern frontiers of the galaxy, wreaking harm like a lone predator against the hated Traitors of Horus. Like all those who had escaped the Drop Site Massacre, they had cut their warplate with the names of the fallen, and the black armour of these two Morlocks was inscribed with intricate scriptwork, each name inscribed over the cuts, tears and burns inflicted on Istvaan V. But these warriors had a name acid-etched on their shoulder guards that marked them out as special even in a brotherhood of remarkable warriors, that of Ferrus Manus, for they had seen their Primarch die at the treacherous hands of his brother Fulgrim. Like other veterans of the Xth Legion, they had refused to repaint or repair their armour until the Traitor who had murdered the Iron Hands' Primarch was dead. Thoic’s face was bisected by a curling series of scars inflicted by a laughing swordsman of the Emperor's Children, while Numen’s features had the plasticised sheen of synth-skin after a close-range plasma detonation had seared the ceramite of his battle helm to his skull. His flash-burned eyes had been replaced by simple targeting optics, but his hearing was almost entirely gone.
- Frater Thamatica, "Ironwrought" - Frater Thamatica was an Iron Father of the Iron Hands Legion, a member of the Morlocks and a survivor of the killing fields of the Urgall Depression on the world of Istvaan V. It was Thamatica who helped establish contact with the disparate groups of Loyalist forces who had escaped the Drop Site Massacre, and he helped develop a stratagem for their survival. With the Xth Legion too scattered to function in a traditional battlefield role, its surviving commanders found their own way to fight back. Thamatica escaped alongside the remnants of the Xth Legion and joined the ad hoc group of survivors of that battle aboard the Iron Hands Strike Cruiser Sisypheum as it fled the Istvaan System. Following the Drop Site Massacre, Thamatica had become the longest-serving Iron Father left alive in the Xth Legion.
- Vaakal Desaan - Vaakal Desaan served as a Morlock and the 9th Clan Company Captain during the Great Crusade and Horus Heresy eras. Desaan was known to be a staunch adherent to the Creed of Iron, which espoused that "Flesh is Weak." His ostensible elitism and lack of human empathy often spilled over into disdain for mortals, and sometimes worse. Desaan's grizzled face was a patchwork of scars from the numerous campaigns he had taken part in during the Great Crusade.
- Erasmus Ruuman - Erasmus Ruuman served as a Morlock and the Captain of the 13th Clan Company Ironwrought during the Great Crusade. Ruuman was killed by xenos forces during the difficult Imperial Compliance action on the world of One-Five-Four-Four.
- Horus Heresy: Collected Visions
- Fulgrim (Novel) by Graham McNeill, pp. 97, 300-301, 303, 314, 338, 369-370, 373, 375, 380, 383, 385-388, 392, 400
- The Primarchs (Anthology), " “Feat of Iron,” by Nick Kyme pp. 60, 64-65, 67-70, 76, 80, 83-85, 87, 94, 105
- Angel Exterminatus (Novel) by Graham McNeill, pp. 60, 83-84, 86-88, 101-104, 108, 113-115, 136-137, 142-143, 158-159, 162-168, 172, 174, 212, 216-217, 222, 271, 282