Primarch - Loyalists: Ferrus Manus - Ferrus Manus of the Iron Hands was killed at the Drop Site Massacre on Istvaan V at the start of the Horus Heresy by Fulgrim of the Emperor's Children who presented his head to Horus.Sanguinius - Sanguinius of the Blood Angels was slain by Horus on the bridge of his Battle Barge and flagship Vengeful Spirit in orbit above Terra at the end of the Siege of Terra after refusing to join him and serve the Ruinous Powers of Chaos.Lion El'Jonson - Lion El'Jonson of the Dark Angels returned to his homeworld of Caliban only to discover that his friend and second-in command Luther and the Dark Angel garrison left on their homeworld had turned against him and chosen to serve Chaos. He led a strike force of his own Loyalist Dark Angels against the Traitors, who were called the Fallen Angels. He disappeared amongst the inferno as the world was blasted apart by a Warp Storm caused by the Fallen Angels' adherence to Chaos and a powerful bombardment from his ships in orbit. He sleeps deep within the Rock, the biggest remaining piece of Caliban and the current mobile fortress-monastery of the Dark Angels. Only the Emperor and the Watchers in the Dark know of this great secret.Jaghatai Khan - Jaghatai Khan of the White Scars disappeared while pursuing Drukhari pirates into a Webway portal after they had managed to raid the world of Mundus Planus. There are rumours that he fights there still against the Drukhari, lost in the twisting paths of the Webway. After nine thousand years, it seems highly unlikely, but not impossible that Jaghatai Khan still lives.Leman Russ - Leman Russ of the Space Wolves disappeared into the Eye of Terror. The Space Wolves have a legend that says Russ went on a quest to find a means to cure the Emperor and restore him to full consciousness. His final words before his disappearance indicate that he would return during the Wolftime (the Last Battle between Order and Chaos). It is also said that Leman Russ led the 13th Company of the Space Wolves into the Eye of Terror and ordered them to hunt down the Traitor Legions which had fled into that vast Warp rift, particularly the Thousand Sons, the Space Wolves' most hated adversaries.Rogal Dorn - Rogal Dorn of the Imperial Fists died fighting on the bridge of the Chaos Despoiler-class Battleship Sword of Sacrilege alongside a company of his sons after he led a contingent of Imperial Fists in an attack on the massed armada of the 1st Black Crusade in the late 31st Millennium with a vastly outnumbered force. He had launched the hopeless assault in the hopes of delaying the Chaos offensive upon the Imperium until reinforcements could arrive. He died long after many of his Loyalist brother Primarchs had already passed on. His skeletal remains, weapons and power armour were recovered from the wreck, even as most of the Chaos starship was destroyed during the conflict. Today, Dorn's skeletal fists have been separated from the rest of his remains and are housed in the holiest shrine of the Imperial Fists Chapter onboard their mobile fortress-monastery the Phalanx, preserved in stasis for all time and inscribed with the names of every Imperial Fists Chapter Master to have led the sons of Dorn since his death. Only a Chapter Master has the right to inscribe his name and heraldry upon their sacred bones. At the same time, Dorn's skeletal corpse, without the hands, was also placed by the Imperial Fists within another chapel on the Phalanx, embedded within a block of clear amber that has been contoured to match the body's form.Roboute Guilliman - Roboute Guilliman of the Ultramarines was struck down with an envenomed Chaos blade by his brother Primarch Fulgrim. His body was perfectly preserved in a stasis field at the heart of the Temple of Correction on the world of Macragge. It was long rumoured that he was still alive and that his wound was slowly healing, something considered physically impossible in a stasis field. The truth of this rumour has proved to be moot, but was seen by many (including the Ultramarines Captain Uriel Ventris) as mere wishful thinking. However, during the Ultramar Campaign in 999.M41, Roboute Guilliman was resurrected through a combination of the technical skill of Archmagos Dominus Belisarius Cawl and the psychic might of Ynnead, the Aeldari god of the dead, as directed through his priestess Yvraine, the leader of the Ynnari. After his awakening, Guilliman led the Terran Crusade to the Imperium's Throneworld to meet with his father the Emperor of Mankind for the first time in 10,000 standard years. In the wake of that meeting, Guilliman named himself the Lord Commander of the Imperium once more and launched the Indomitus Crusade to take the fight back to the encroaching enemies of Mankind.Vulkan - Vulkan of the Salamanders disappeared. The position of Chapter Master, filled by the Captain of the 1st Company of the Salamanders ever since, is considered to be a regency as the Salamanders believe that Vulkan will one day return and lead them on a great crusade against Chaos.Corvus Corax - Corvus Corax of the Raven Guard was racked by guilt and shame for what had happened to his Chapter when he had approved the use of heretical genetic manipulation in order to rapidly increase the numbers of the shattered Raven Guard after the Drop Site Massacre. In order to rebuild quickly the strength of his Legion from the Dropsite Massacre on Istvaan V, Corax had ordered the Raven Guard's Apothecaries to accelerate the growth of the Legion's gene-seed organs, producing more Space Marines than the process normally allowed, but these changes also degenerated or mutated the Legion's gene-seed, causing many Raven Guard Neophytes to become hulking, mutant monsters. Riddled with guilt over what he had done, Corax euthanised all of the mutated Astartes and then locked himself away within his sanctum, the Raven's Tower. Exactly one standard year later he left his tower, haggard and gaunt, and took a small shuttlecraft equipped with a Warp-Drive into the Immaterium with the words, "Nevermore." Corax's shuttle was last monitored setting a course through the Warp for the Eye of Terror. Corax went on to hunt the Traitor Primarchs, seeking revenge for the deaths of his sons during the Drop Site Massacre. At some point his long exposure to the corrupting energies of the Warp led to his transformation into a creature made of shadow itself. Using his new abilities, Corax wreaked havoc on a Word Bearers Daemon World in the Eye of Terror. Far beyond the abilities of average Word Bearers Heretic Astartes to defeat, the Daemon Primarch Lorgar himself appeared before Corax and the two engaged in a vicious duel. Corax managed to dominate the battle, forcing Lorgar to retreat and close the portal through the Warp from which he had come. As Lorgar vanished, Corax vowed that he would hunt down and slay the Daemon Primarch and destroy his Legion once and for all.