Knights-Errant - Notable Knights-Errant: Twenty original members of the Knights-Errant were recruited directly by Malcador with others being recruited second-hand by other Knights-Errant and agents of the Sigillite. Notable members include the following Astartes.Nathaniel Garro (Death Guard) - Former battle-captain of the 7th Great Company of the Death Guard, it was Nathaniel Garro who brought word of the Warmaster Horus' betrayal at Isstvan III to Terra aboard the Eisenstein. He was the first to be recruited as Malcador's Knight-Errant, and was made the Sigillite's Agentia Primus, the leader of the Knights-Errant and Malcador's most important Imperial agent.Tylos Rubio (Ultramarines) - A former codicier of the Ultramarines Legion, after the Decrees of Nikaea forbidding the use of psyker abilities, he was reassigned to the Legion's 21st Company, and was later recruited by Nathaniel Garro during the infamous Battle of Calth.Macer Varren (World Eaters) (KIA) - A former captain of the 12th Company of the traitorous World Eaters Legion, Macer Varren remained steadfastly loyal to the Emperor, despite his Legion throwing in their lot with Horus. He would later be recruited by Nathaniel Garro into the ranks of the Chosen of Malcador. Varren would serve with the Knights-Errant for most of the Horus Heresy, and was killed during the Battle of the White Mountain on Terra in the days just before the Siege of Terra began. After being mortally wounded, Varren was possessed by the Daemon of Nurgle known as the Lord of Flies. However, he possessed enough remaining willpower to overcome the daemon and destroy himself before he was forced to kill his comrade Garviel Loken.Garviel Loken Sons of Horus -  Garviel Loken was the captain of the Sons of Horus (originally Luna Wolves) Legion's 10th Company during the last days of the Great Crusade and up until the Isstvan III Atrocity that initiated the Horus Heresy. He was also a member of the Mournival, Horus' cadre of four senior unofficial advisers and confidants. During the betrayal at Isstvan III, Loken fought on the side of the Loyalists, and eventually faced down his former comrade, First Captain Ezekyle Abaddon in battle. He was gravely wounded and left for dead, and was thought to have died in the Traitors' final orbital bombardment of Isstvan III. Miraculously, he survived the onslaught and was rescued by Nathaniel Garro and Macer Varren many solar months later, later becoming a Knight-Errant.Iacton Qruze (Sons of Horus) (KIA) -  Iacton Qruze, "The Half-Heard," was the captain of the 3rd Company of the Sons of Horus Legion during the Great Crusade and the opening days of the Horus Heresy. Qruze was a very old Space Marine who was a native of Cthonia. During the events of the Isstvan III Atrocity, he escaped alongside two civilians of the Remembrancer order and fled with other Loyalists aboard the Death Guard frigate Eisenstein to bring the news of Horus' betrayal to the Emperor on Terra. He was later recruited by the Sigillite to become a Knight-Errant. He died at the hands of Horus himself during a failed assassination attempt aboard the Warmaster's flagship, the Vengeful Spirit.Severian (Sons of Horus) - Severian was originally a Luna Wolves and then Sons of Horus Legionary who was chosen to serve as a part of the Crusader Host upon Terra at the outset of the Great Crusade, serving on the Throneworld for approximately 170 standard years, and was absent for the majority of the Great Crusade before Horus' betrayal at Isstvan III. Due to his affiliation with a Traitor Legion, he was imprisoned in Khangba Marwu with the other Crusader Host Legionaries, but later escaped. He was eventually tracked down by the expert hunter, Yasu Nagasena, who fought the Luna Wolf, and was easily bested. He was captured by agents of the Sigillite and recruited to become a Knight-Errant. His latent psychic precognitive abilities would be put to use in forming the Grey Knights Chapter at the Heresy's end.Tubal Cayne (Iron Warriors) (KIA) - Tubal Cayne was an Iron Warriors Astartes who was chosen to serve as a part of the Crusader Host upon Terra at the outset of the Great Crusade. With Horus' treachery revealed, he was imprisoned in Khangba Marwu with the other Crusader Host Legionaries, but eventually had his sentence commuted by the Sigillite, and was offered a place within the ranks of the Knights-Errant. He was killed aboard the Sons of Horus' flagship, the Vengeful Spirit, during the failed assassination attempt on Horus, after the Knights-Errant infiltrated the vessel following the Battle of Molech.Ares Voitek (Iron Hands) -- An Iron Father and member of the stoic Iron Hands Legion, Ares Voitek was recruited by agents of Malcador sometime following the Drop Site Massacre at Isstvan V. He may possibly have been a survivor of that disastrous battle. He was later critically injured aboard the Sons of Horus' flagship Vengeful Spirit during the failed Loyalist attempt to assassinate Horus. He was put into an induced coma to heal from his grievous wounds.Bror Tyrfingr (Space Wolves) (KIA) - Bror Tyrfingr was an Astartes of the ferocious Space Wolves Legion and fought during many campaigns of the Great Crusade and Horus Heresy. After Horus' treachery at Isstvan III was revealed, Malcador, Rogal Dorn and Bror's Primarch Leman Russ hatched a plan to infiltrate a Knights-Errant strike force aboard the Warmaster's flagship in order to assassinate him, and hopefully end the Horus Heresy. Bror was ordered by his primarch to become a member of the Sigillite's Knights-Errant. During the subsequent failed attempt, the team was eventually discovered and forced to fight for their lives. In the ensuing conflagration, Bror managed to rip out the throat of Tormageddon, a Daemon that resided within the physical remains of the brain-dead Son of Horus Ger Gerradon. He eventually fled aboard the stealth ship Tarnhelm after it was forced to fire into Lupercal's Court, Horus' self-styled throne room aboard his flagship, which created a distraction and allowed the Knights-Errant to make good their escape. With the Sigililite's agents having failed, Leman Russ mobilised the diminished Space Wolves Legion in his own attempt to storm the Vengeful Spirit and slay Horus. Russ "borrowed" Tyrfingr from the Knights-Errant and led the VIth Legion against the Sons of Horus. Reunited with his former pack, Tyrfingr penetrated deep inside the Arch-traitor's flagship, destroying one of the vessel's magazines before being harassed by Traitor forces all the way back to their extraction point. Still deep in the bowels of the Vengeful Spirit, Tyrfingr and his men were ambushed by a party of Justaerin Terminators led by the Sons of Horus' baleful First Captain Ezekyle Abaddon. His pride wounded by Tyrfingr's first successful escape, Abaddon had chosen the site of his ambush well. With no means of escape, Tyrfingr and his companions died under the fire of the Justaerin's bolters.Rama Karayan (Raven Guard) (KIA) - Rama Karayan was a Legionary of the Raven Guard who served during many campaigns of the Great Crusade and Horus Heresy. After the outbreak of the Heresy, he was recruited to become a member of the Sigillite's Knights-Errant. He would later befriend the White Scars Apothecary Altan Nohai, who taught hin Chogorian martial arts. During the failed assassination attempt aboard the Sons of Horus' flagship Vengeful Spirit, Karayan was slain at the hands of Grael Noctua, captain of the Sons of Horus' 25th Company, and a member of Horus' Mournival.Altan Nohai (White Scars) (KIA) - Altan Nohai was a former Apothecary of the White Scars Legion during the Great Crusade and the opening days of the Horus Heresy, before later joining the ranks of the Sigillite's Knights-Errant. He befriended the Raven Guard Rama Karayan, and taught him the fighting methods of Chogoris tribesmen. Nohai was later killed aboard the Sons of Horus flagship Vengeful Spirit during the Knights-Errant's failed assassination attempt on the Warmaster Horus.Callion Zaven (Emperor's Children) (KIA) - Callion Zaven was a Terran-born Veteran Astartes of the Emperor's Children Legion during the Great Crusade who fought in the earliest Imperial campaigns to reconquer the Sol System. He saw fighting among the moons of Jupiter during the early years of the Great Crusade where he was gravely wounded, before the discovery of his Primarch Fulgrim on the world of Chemos. By the time he got out of the Apothecarion, his Legion had already moved on without him and he soon found himself reluctantly serving as his Legion's emissary in the Crusader Host, and would do so for many solar decades, until Horus' betrayal was revealed at Isstvan III. With Horus' treachery public, he was imprisoned in Khangba Marwu with the other Crusader Host Astartes, but eventually had his sentence commuted by the Sigillite. Zaven was offered a place within the ranks of the Knights-Errant. He was killed aboard the Sons of Horus' flagship, Vengeful Spirit during the failed Loyalist assassination attempt on Horus.Vardas Ison (Blood Angels) - Vardas Ison was a former Librarian of the Blood Angels Legion who was later recruited into the ranks of the Knights-Errant. For unknown reasons, he vehemently hated his old Legion.The Nemean (Dark Angels) - His origins unknown, it was believed that the Nemean was a former officer of the Ist Legion -- the Dark Angels. Unconfirmed rumours circulated that he was a survivor of the Rangdan Xenocides, the apocalyptic conflict that saw the nascent Imperium threatened with destruction, and he had already entered into the legends of the Legiones Astartes long before the Horus Heresy. He was later separated from his Legion and established the Dark Brotherhood, an infamous and feared Blackshield force that sought to carve out their own domain deep within the Eridayn Cataract during the middle years of the Horus Heresy. He garnered a reputation throughout the Pale Stars, and was later recruited by Nathaniel Garro to join the ranks of the Knights-Errant.Helig Gallor (Death Guard) - Helig Gallor was a former Astartes of the Death Guard Legion, known to be grave but strong of character. He faithfully served his Legion during many campaigns of the Great Crusade. During the Horus' betrayal at Isstvan III, he, along with seventy other Loyalist members of the Death Guard, fled with Battle-Captain Nathaniel Garro aboard the frigate Eisenstein, to carry word of the Warmaster's treachery to Terra. He, along with his fellow Death Guard Legionaries who became known as "The Seventy", were later remanded into the custody of the Sisters of Silence within the Somnus Citadel upon Luna, until their fate could be determined by the Regent of Terra. He was then offered the chance to join the ranks of the Knights-Errant.Bajun Kyda (Death Guard) (KIA) - Bajun Kyda, known also as "The Bull of the Seventh," was a former Astartes of the Death Guard's 7th Great Company during the Great Crusade. He would later be a member of "The Seventy," the Loyalist Death Guard Astartes who fled alongside Battle-Captain Garro aboard the frigate Eisenstein during the Isstvan III Atrocity. Remanded into the custody of the Sisters of Silence within the Somnus Citadel upon Luna, Kyda chafed at inaction and thirsted for the rush of battle. He was later offered the chance to join the ranks of the Knights-Errant, but was tragically killed during his first mission upon the world of Proxima Majoris.Dravian Klayde (Raven Guard) (KIA) - Dravian Klayde, known as "The Carrion" due to the terrible wounds he received during the Breg-shei Eradication, was a former sergeant of the Raven Guard Legion. Undergoing extensive augmetic repairs, Klayde was selected for training on Mars to become a Techmarine but would never achieve this status, as the very day he and his fellow Space Marines were to take their Covenant, the Schism of Mars erupted. Escaping to Terra, he was invited to join the ranks of the Sigillite's Knights-Errant, and was later sent back to Mars to undertake a dangerous mission -- to destroy Vertex Australis, and wipe out all life on Mars, thereby cutting off the Traitors' supply of arms and equipment. During this valiant attempt he seemingly died fighting his former friend and ally, the now-corrupted Iron Warrior Aulus Scaramanca.Revuel Arvida (Thousand Sons) - Revuel Arvida was a sergeant of the Thousand Sons Legion's 4th Fellowship and a member of its Corvidae Cult during the Great Crusade and the opening days of the Horus Heresy. His Fellowship later returned to their homeworld several solar months after the Scouring of Prospero to seek out any survivors. But instead, he and his fellow Astartes were waylaid by a force of World Eaters, and all of them were killed, with the exception of Sergeant Arvida. After an unknown amount of time, he discovered a White Scars force, led by Primarch Jaghatai Khan, upon Prospero. They were there to ascertain what exactly had occurred, as they were still unsure as to which side of the galaxy-wide conflict they should side with. Making himself known, he later fought alongside the White Scars against a strike force of elite Death Guard, led by their Primarch Mortarion. Arvida was taken from the planet's surface to recover from wounds he received in the battle, and would later join the White Scars in their fight against the Traitors. He would also play an instrumental role in helping the Vth Legion circumvent the raging Ruinstorm, finding a safe route back to Terra. After guiding the White Scars fleet to the outskirts of the Sol System, he fell into a coma, succumbing to "the Flesh-Change," a debilitating physical mutation that affected the Thousand Sons' gene-seed. He was later taken by Khalid Hassan, an agent of the Sigillite, who promised the attendant White Scars Stormseers that they could help Arvida, as they had been waiting for his imminent arrival. Arvida was transformed in an arcane ritual conducted by Malcador the Sigillite into an amalgam of Arvida and a psychic fragment of the soul of the Primarch Magnus the Red which had been left on the Throneworld after his ritual incursion into the Imperial extension of the Webway to warn the Emperor of Horus' betrayal. The new hybrid being chose to call himself Ianius, later known as Janus, who would go on to become the first Grey Knights Supreme Grand Master.Fel Zharost (Night Lords) - Zharost was the former Chief Librarian of the Night Lords Legion. Within a few standard years of his Legion's reunification with their Primarch Konrad Curze on Nostramo, Zharost was one of the ill-favoured and withering remnants of Terran-born Astartes who still served in the VIIIth Legion. After the Emperor's Decree Absolute during the Council of Nikaea banning the use of psykers in the Space Marine Legions, Zharost sought a private audience with First Captain Jago Sevatarion, who had been left in temporary command of the Legion in their primarch's absence. He demanded that Sevatarion render judgment against their Legion's Librarius -- and himself. Sevatarion's judgement was severe. Zharost was cast out of the Night Lords and would no longer be considered an Astartes of the VIIIth Legion -- his hands were to be stained red. The first captain condemned Zharost to death should they ever meet again. Instead, the Chief Librarian returned to Terra, to the place of his birth, amongst the prison sinks beneath Albia. Eventually he was hunted by an unknown assailant, an Astartes clad in plain grey and unburnished power armour, and captured. Facing his imminent execution, he utilised his psychic powers to show his would-be executioner his past. He also looked into the Knight-Errant's mind and was shocked when he saw the memories of betrayal and oath-breaking. Once he recovered, the Knight-Errant of Malcador informed the former Chief Librarian that he had not come to judge him. For that right belonged to another. Understanding his fate, Zharost willingly left with the Knight-Errant, and soon found new brotherhood among a different fellowship that saw no stigma in his continued use of his psychic powers.Umojen (Salamanders) — Umojen was the former Chief Librarian of the Salamanders Legion. He voted in favor of maintaing a Legion Librarius during the Council of Nikaea. Later, he became one of Malcador the Sigillite's Knights-Errant.Balsar Kurthuri (Raven Guard) — Kurthuri was the former Chief Librarian of the Raven Guard Legion. Balsar Kurthuri was a Librarian in the Raven Guard Legion during the Great Crusade, until the Edict of Nikaea when he was then forced to become a Legionary. He would later take part in the Horus Heresy and was one of the few members of his Legion to survive the Drop Site Massacre. Afterwards, Balsar was chosen to become his depleted Legion's Chief Librarian when his Primarch Corax reinstated the Raven Guard's Librarius. In the later years of the Horus Heresy, Balsar's standing within the Legion would change once more after a meeting with his fellow Librarian Fara Tek. Tek had just rendezvoused with his Legion where it was gathering in the Rosario System and shared with Balsar a psychic message he had received before he had rejoined the Raven Guard. Though the message was not clear, Balsar gathered from it that the Primarch Leman Russ' life was in danger, but little else. He could not tell Balsar where the message had come from, though he had been able to receive another message from a nearby Space Wolves strike cruiser that was being attacked by the Word Bearers and needed aid. Balsar immediately brought this information to Corax, who dispatched Captain Agapito Nev and the Battle Barge Providence to save the Space Wolves strike cruiser. Agapito succeeded in doing so and brought the strike cruiser's commander, Rathvin, to meet with Corax. The Space Wolf proceeded to inform the Raven Guard's primarch that Leman Russ was indeed in danger, as his Legion had been cornered on the world of Yarant Three by Horus' forces, which heavily outnumbered them. Rathvin would leave shortly afterwards, to join his his Legion in battle, and Corax quickly gathered his commanders and informed them the Raven Guard were going to Yarant Three to aid the Space Wolves. Balsar was shocked when his primarch informed him that he would not be joining the rest of his Legion and that he had also been stripped of his title of Chief Librarian. Corax had once again disbanded the Raven Guard's Librarius. For reasons unknown to Balsar, Corax had grown deeply mistrustful of psykers and wanted his former Librarians to be immediately separated from his Legion and sent back to Terra. Though Balsar was eventually able to convince his primarch to let his fellow psykers remain with the Legion as long as they did not use their powers, the former Chief Librarian's fate was sealed. Corax commanded him to depart for Terra at once and told Balsar that when he arrived there, he was to present himself to Malcador the Sigillite, who would decide what would become of him. When Kurthuri arrived in the Sol System accompanied by Captain Noriz and his Imperial Fists and the Legio Custodes Arcatus and his Custodians, the Custodian Ludivicus gave the order to hunt the Librarian down. Arcatus immediately obeyed, attacking Kurthuri on the bridge, but Noriz attempted to help him escape the ship. Cornered by Arcatus, Noriz was killed by the Custodian, but Kurthuri was spared when he backed down from using his psychic powers to avenge the Imperial Fists captain's death. Kurthuri was brought before Malcador the Sigillite and presented with a suit of grey power armour by Umojen, becoming one of the Knights-Errant, for his restraint had shown that he would be loyal to the Emperor's commands even when faced with death. Later, Kurthuri may possibly have become the founding Grey Knights Grand Master Ogen.Varskjold - Varskjold was a member of the Knights-Errant from an unknown Space Marine Legion who was aboard the Imperial Fists starship Xanthus when it was brought down on the world of Algonquis. The ship had been bound for the Sol System, and was able to send an astropathic message encoded with non-Legion ciphers before it crashed. After the ship was boarded by the Death Guard Chaplain Morgax Murnau and the Graven, Varskjold ordered the weapon batteries overloaded, causing the ship to sink into the toxic sludge of the planet's surface.Dio Promus (Ultramarines) (KIA) - Promus was the former Chief Librarian of the Ultramarines.  He voted in favor of maintaining a Legion Librarius during the Council of Nikaea. He later was recruited into the Knights-Errant. As a member of the Knights-Errant, Promus was tasked by Malcador the Sigillite to select Astartes candidates for the Titan Project, those who would eventually become Grey Knights, and was expected to kill those who were seen as too mentally weak to face the burdens of becoming those psychic Space Marines. Promus went on to lead a mission at the orders of Malcador to recover the psychic Shards of Magnus. Accompanied by Yasu Nagasena and Space Wolves led by Bodvar Bjarki, their mission brought them to the xenos void station psyker prison of Kamiti Sona, the world of Aghoru, and finally Nikaea itself where they fought against the Thousand Sons cabal commanded by Ahriman. On Nikaea, Promus was struck down trying to fight a shard of Magnus, blasted by Magnus's power, but Yasu Nagasena stepped in to protect him from a swarm of Daemons. After the shards of Magnus merged and left with Ahriman for the Planet of the Sorcerers, Promus was confronted by Bjarki who learned of his past murders of Loyalist Astartes from the Daemon Fatewoven. Promus admitted the Daemon's claims were true to Bjarki but refused to explain the secrets he was bound to keep by the Sigillite, including why the killings had been necessary. Unable to forgive Promus' actions, on the orders of Bjarki, Svafnir Rackwulf ended the Knight-Errant's life in response. Dio Promus' friend Lemuel Gaumon then took Promus' name as his own.Fyodor Stromgren (Space Wolves) - Fyodor Stromgren was a member of the Space Wolves during the Great Crusade and Horus Heresy. Originally assigned by his Legion to watch over the Night Lords Primarch Konrad Curze at the start of the Horus Heresy, Curze had Fyodor and his packmates captured and mutilated. All save Fyodor died, and the Night Haunter sent the grievously wounded Space Marine back to Terra to serve as a message to other Loyalists. However Fyodor's body was recovered by the Knights-Errant, and Malcador the Sigillite demanded he be revived by all means available save interment within a Dreadnought sarcophagus. It is likely he thereafter joined the Knights-Errant. Stromgren may have became the founding Grey Knights Grand Master Yotun.Antaka Cyvaan (Raven Guard) - Cyvaan was a Librarian of the Raven Guard during the Great Crusade and Horus Heresy. He was later inducted into the Knights-Errant and accompanied Dio Promus and Yasu Nagasena to Nikaea during the Knights-Errant's hunt for the Shards of Magnus. It is likely that either he or Balsar Kurthuri became the founding Grey Knights Grand Master Ogen.