Ignatius Grulgor was originally the Commander (Captain) of the Death Guard Legion's 2nd Great Company during the last days of the Great Crusade and the first battle of the Horus Heresy in the early 31st Millennium. He chose to follow Horus, his traitorous Primarch Mortarion, and First-Captain Typhon's decision to serve Chaos and overthrow the Emperor of Mankind, installing Horus as the true Emperor to rule over the Imperium of Man. Grulgor was slain during the flight of the Imperial frigate Eisenstein from the Battle of Istvaan III by his long-time rival Battle-Captain Nathaniel Garro. Grulgor was resurrected through the influence of the Chaos God Nurgle as one of the first Plague Marines, and after being defeated for a second time aboard the Eisenstein by Garro, his soul was banished into the Warp, where the Plague Lord eventually raised him as one of his Daemon Princes. In 999.M41 Grulgor would return to haunt the Imperium during the Forces of Chaos' assault upon Medusa V.
Ignatius Grulgor was born on the bleak and poisonous world of Barbarus, the homeworld of the Primarch Mortarion and later the Death Guard Legion. He grew up on that harsh Feral World, living in the human settlements in the valleys below the foreboding mountainous crags, perpetually wrapped in poisonous fog. These mountains were the home to horrific warlords who possessed fantastic sorcerous powers and horrific appetites. Grulgor grew up amongst the human settlers eking out a bleak existence, for they lived lives of unrelenting terror. By day they lived beneath the dim sun which never burned completely through the fog, and cringing by the firelight after dark from the terrible creatures that moved unseen from above. When at last the Emperor came to Barbarus and discovered the gaunt warrior foundling named Mortarion who lead its oppressed people, he knew he had located the Primarch of the XIV Legion. On the day of Mortarion’s coronation as Primarch, a good majority of the XIV Legion had been of Terran stock, men born on Terra or within the confines of the Sol System, but slowly that number had dwindled, and as new recruits joined the Death Guard's fold they came only from Barbarus. Grulgor was one of those initiated into Mortarion’s Legion from Barbarus. By the last days of the Great Crusade in the early 31st Millennium, only a comparative handful of Terrans remained in the Legion.
During the Great Crusade, Grulgor rose to command the XIV Legion's 2nd Great Company. The Death Guard differed from many of their brother Legions in the manner of their command structure and rank system. Tradition had it that the XIV Legion should never number more than 7 great companies, although those divisions held far more men than those of other Astartes cohorts like the Space Wolves or the Blood Angels; and whilst many Legions had the tradition of giving the honorific of "First-Captain" to the commanding officer of the elite 1st Great Company, the Death Guard also held two more privileged titles, to be bestowed upon the leaders of the 2nd and 7th Great Companies, respectively. Thus, although they held no actual seniority over one another, Captain Ignatius Grulgor of the 2nd Great Company could carry the rank of "Commander" if he so wished, just as Nathaniel Garro, as Captain of the 7th Great Company, was known as "Battle-Captain."
Grulgor was forever on the edge of arrogance, snarling instead of speaking, judging others instead of considering the ramifications of his own behaviour. Grulgor detested the Terran-borne Battle-Captain of the 7th Great Company, Nathaniel Garro, as he felt that Garro was unfit to be a Death Guard. Garro's high-handed and superior attitude simply grated on Grulgor's nerves. Grulgor felt that Garro thought too much of himself and that he felt that he was better than the rest of the Legion because of his Terran birth, too proud and too good for the rest of them. He often referred to the staunch and reserved Battle-Captain as "Straight-Arrow Garro." Grulgor seemed to reserve his hatred only for Garro, as the other Terran-born Battle-Brothers did not choose to promote the Legion's old ways as if they were suffocating chains. Many of the newer Astartes in the Legion like Gulgor who had been recruited from Barbarus felt that before their Primarch had brought new blood into their Legion from his homeworld, there were many rituals and traditions within the ranks of the XIV Legion that had served only to hold the Death Guard back from further accomplishment. Garro had made it a habit to hold onto these outdated traditions, including his determination to maintain a housecarl to attend to his armour and weapons. This was even more of a joke to the Death Guard who thought like Grulgor because the normal human that attended him was a former Death Guard Aspirant who had failed the final trials to become an Astartes of the Legion. Grulgor boasted that if he had been made First Captain, the first thing he would do was to abolish outright these outmoded traditions. Like many of his fellow Barbarus-born Battle-Brothers, Grulgor's loyalty was to Mortarion first and the Emperor of Mankind second. When Horus proposed his great rebellion to his brother Primarchs, and Mortarion responded in the affirmative that he would support Horus' great betrayal, Grulgor would support his Primarch's course to the hilt.
Towards the end of the Great Crusade relations amongst the various Expeditionary Fleets had become strained ever since Horus had been mortally injured at the moon of Davin and after he returned from his miraculous healing on that world at the hands of the sinister shamans of the Temple of the Serpent Lodge. Upon his return to the orbiting fleet of his own 63rd Expeditionary Fleet, Horus' fealty had changed, for he now secretly conspired to overthrow the Imperium of Man and usurp the Emperor’s throne, to become the new Master of Mankind. Renouncing his oath to the Emperor, Horus led his Legion, renamed the Sons of Horus, into worship of the myriad Chaos Gods in the form of Chaos Undivided. He then sought to turn many of his fellow Primarchs to the service of Chaos, and succeeded with Angron of the World Eaters, Fulgrim of the Emperor's Children and Mortarion of the Death Guard, who were the first of many to follow. Grulgor was a member of the secret warrior lodge within the Death Guard Legion, a custom that had spread through all of the Astartes Legions from the Luna Wolves over the course of the Great Crusade following the Luna Wolves' original conquest of Davin, a world whose people had long been worshippers of Chaos. There had been talk in the warrior lodges of many of the Legions of how far away the Emperor was and of growing discontent over his decision to place the administration of the Imperium in the hands of the civilians of the Council of Terra. Horus exploited these rumblings of discontent to propose a galaxy-wide insurrection against the Emperor on a scale that had never been seen before. He would launch the opening phase of this terrible conflict, later known as the Horus Heresy, on the rebellious Imperial world of Istvaan III.
The Council of Terra had recently charged the Warmaster with retaking the world of Istvaan III, after the Slaanesh-corrupted Imperial Governor Vardus Praal had declared the Istvaan System an independent principality and seceded from the Imperium. This order played right into Horus’ schemes, furthering his ambitions to overthrow the Emperor. Though four Legions under his direct command had already pledged their allegiance to his traitorous cause, there remained within each Legion elements who were still loyal to the Emperor. These men were chiefly those older Astartes who had been born on Terra and had been raised into their Legions before their Primarchs had been recovered. These Loyalist elements constituted approximately one-third of each of the 4 Traitor Legions. Horus personally chose all the units for the assault on Istvaan III’s planetary capital that was known as Choral City. He picked only the Astartes of the gathered Legions who he and his fellow Primarchs knew would remain loyal to the Emperor. He planned to unleash an orbital virus-bombing of Istvaan III once the Loyalist elements of the Legions were engaged against the rebel forces, wiping out all life on the planet and eliminating two birds with one stone.
Before the mission began, First-Captain Typhon pulled Commander Grulgor aside and spoke to him of their Primarch’s desire to bring Garro to the Warmaster’s banner over the Emperor's, but they both knew that Garro would never betray the Master of Mankind. He was too much the Emperor’s dutiful warrior. Realising Typhon's intent, Grulgor deduced that the time for the Traitors to act against the Imperium had arrived, as he saw Horus' true intention emerging in the unusual pattern of mission assignments on Istvaan III granted to specific units from the Legions, instead of complete companies. Grulgor realised that the Warmaster sought to isolate those elements of the soon-to-be Traitor Legions that did not share his convictions. When the turning point arrived, Typhon informed Grulgor that there were certain duties that Horus and Mortarion would want him to perform. Grulgor relished his part in this conspiracy against Garro, whom he had long found insufferable.
Garro had recently received grievous wounds facing the Istvaanian rebels on the outermost world of the Istvaan System that was known as Istvaan Extremis. His wounds necessitated him having one of his legs replaced with a bionic substitute. The Legion’s Apothecaries declared him not fully healed and therefore Garro was deemed unfit for battlefield operations. Typhon ordered Garro to be stationed aboard the Death Guard frigate Eisenstein during the assault on Istvaan III, while Commander Grulgor would also be assigned to the starship in order to keep a close eye on the Terran-born officer. On Typhon's orders, Grulgor secretly transported a shipment of Life-Eater virus bombs on a Thunderhawk over to the Eisenstein. This biological weapon was a deadly engineered viral strain of extreme lethality which would be used against the Loyalist forces on the planet’s surface. Unknown to the traitorous Grulgor, he was being secretly observed by Garro’s housecarl Kaleb Arin and the 7th Great Company's Apothecary Meric Voyen. Arin ran to the frigate's bridge to warn his lord of Grulgor's intentions.
Garro, two Astartes from his Command Squad and Arin confronted Grulgor. Grulgor made a seditious declaration against the Emperor and that only Horus and Mortarion could command him. He also made known his intention to carry out the will of Horus and Mortarion by unleashing the virus-bombs upon the surface of Istvaan III once Horus gave the order. In the ensuing melee, Grulgor took aim with his Bolt Pistol at the preoccupied Garro but was thwarted by the efforts of Kaleb Arin who instinctively fired his Stub Gun, causing Grulgor to miss his intended target. His errant Bolter round ricocheted off the metal bulkhead and into one of the fragile glass Life-Eater virus warhead spheres that contained the lethal engineered pathogen, releasing its contents into the air. Garro and his two men managed to flee as Arin used his remaining strength to launch himself forward and close the blast shield door, effectively trapping Grulgor and his men. Grulgor and the traitorous Battle-Brothers of his own Command Squad died in agony, suffering the lethal effects of the flesh-devouring Life-Eater virus. With Horus' treachery revealed, Garro chose to flee the Istvaan System in order to carry a dire warning of the treachery unfolding to the Emperor on Terra.
During its escape from the Istvaan System, the Eisenstein sustained serious damage when it was assaulted by First-Captain Typhon’s Battleship Terminus Est, though it managed to just barely make a successful Warp jump into the Empyrean. Once within the chaotic eddies of the Warp, the damaged Eisenstein attracted the attention of the Chaos God Nurgle, the Plague Lord, who had already claimed the Death Guard Legion as his future champions and had no desire to see Horus' rebellion against the Emperor suffer a setback. Because the Eisenstein's Gellar Field had been weakened by the damage the starship had sustained during its flight from the Istvaan System, the Dark God was able to insinuate his malign influence into the vessel. Nurgle's power resurrected Grulgor, his dead Astartes and the ship's crew who had sided with him, creating the first Plague Marines. The ensuing battle between the infected Warp creatures and the Loyalist Death Guard aboard the ship resulted in the death of the vessel's only Navigator. Grulgor, using a newly-created Plague Knife, managed to infect a member of Garro's command squad, the young Battle-Brother Solun Decius, with the terrible daemonic disease known as Nurgle's Rot, and almost triumphed over Garro. However, Garro ordered the Eisenstein to make an emergency transition out of the Warp. Without access to the infernal power of Nurgle sustaining them within the Immaterium, Grulgor and his corrupted brethren were killed, their souls sucked back into the Warp. But the Plague Lord was not yet done with his servant Grulgor.
In 999.M41, shortly after Abaddon the Despoiler's 13th Black Crusade had ended in a stalemate, the Imperial Mining World of Medusa V in the Ultima Segmentum was engulfed in a campaign of slaughter and attrition by the various enemies of Mankind including: the Forces of Chaos, the Dark Eldar, the Eldar, the Necrons, the Orks and the Tyranids. In the intervening years since the end of the Horus Heresy, Ignatius Grulgor had been reincarnated as a powerful Daemon Prince of the Plague Lord. He led a warband of Death Guard Chaos Space Marines in an attack upon the beleaguered planet. During one infamous battle of the conflict, Grulgor led his Plague Marines against the Monastery of Madrigales, a monastery of incalculable value to the Imperium. The Daemon Prince and his minions made short work of the Imperial Guard troops who garrisoned the doomed monastery. Leading the speartip of the assault, Grulgor and his pestilent Traitor Astartes breached the outer gates, taking less than an hour for them to completely overrun the monastery. The Daemon Prince and his forces withdrew after infesting the interior with corruption and pestilence, slaying the entire Astropathic choir and removing the invaluable Imperial databanks. Somehow they managed to spirit themselves off-world before Medusa V was consumed by a vast Warp Storm. Grulgor remains at large, and his current whereabouts are unknown.
- Flight of the Eisenstein (Novel) by James Swallow
- Fall of Medusa V (Worldwide Campaign)