|This article is about the Traitor Titan Legion, for the Imperial Titan Legion see Legio Mortis Metallum|
|Colour Scheme||Info||Legion Symbol|
|Alternative name:||Death's Heads|
|Forge World:||Formerly Mars and Retlaxi, now the Eye of Terror|
|Colours:||Black with red|
The Legio Mortis was formed during the Age of Strife, before the founding of the Imperium itself. According to legends of the Martian Lexmechanics, they were one of the Triad Ferrum Morgulus, the three original Titan Legions created by the besieged Cult Mechanicum during the bloody wars to take the Red Planet from hordes of Cy-Carnivora and Mutants. Legend holds that their original purpose was to serve as the personal guardians of the Fabricator-General's domain and the annihilation of any who would threaten the cult of the Omnissiah. Before the union between the Mechanicum and the Imperium, the Legio Mortis was frequently employed as the Praetorian Guard of the Fabricator-General, punishing any who would dare challenge the authority of the Priesthood, including other Titan Legions. Their status garnered rivalry from other Legions, most notably the Legio Ignatum and Legio Venator.
Even after joining with the Imperium, the Legio Mortis was looked upon with suspicion by the fledging Imperial military staff, many accusing them of being solely loyal to the Fabricator-General as opposed to the Emperor. To both demonstrate and deepen their loyalty to the Imperium, the Legio Mortis was assigned to Horus Lupercal and the 63rd Expeditionary Fleet during the Great Crusade. With the charismatic Primarch they fought over a hundred campaigns, scoring victory after victory. However rather then becoming loyal to the Emperor or his Imperium, the Legio Mortis instead developed a fierce allegiance to Horus himself. Thus it was that they willingly followed their Warmaster into treachery.
The legion was corrupted by the powers of Chaos which enveloped the rebel forces under Horus, and most of the Death's Heads fell towards the vile decay of Nurgle, ironically that same entity which had so disgusted the Titan crews fighting against the hordes of Plague Bearers on the moon of Davin before Horus fell. The Legio Mortis became the most notorious of the traitor Titan Legions. The Legio directly supported Horus before his daemon-possessed treachery against the Emperor. The Legio followed him willingly. When the Horus Heresy began with the virus-bombing of Isstvan III, it was the Legio Mortis which made the landings to scour the corpse-packed hives for the last survivors.
During the Schism of Mars, the Legio Mortis forces supported the traitor Fabricator General Kelbor-Hal, and were the first titan legion to walk in support of Horus. These contingents of Legio Mortis, however, were all but destroyed by Legio Tempestus, save for the Hellstorm Cannon of the Imperator Aquila Ignis. Some say that it was mutated strains of the Life-Eater Virus that was unleashed upon Isstvan III that brought about the final corruption of the Legio. When the Legio Mortis landed on Earth to besiege the Emperor's palace they were warped and mutated almost beyond recognition. The adamantium skins of their Titans were pocked and bubbled with foul effluvia, great tentacles of flesh and metal lashed and their titan heads had been transformed into the visages of daemons. The Legion breached the walls of the Imperial Palace during the siege. The Death's Heads also fought on Maedran, Paramar V, and Tallarn.
The remnants of the Legion fled to the Eye of Terror following the collapse of the rebellion, and from time to time, Chaos Titans bearing the tattered banners of the Legio Mortis have attacked human planets to wreak terrible vengeance on all living things for the defeat of their beloved Warmaster.
- Dies Irae - Imperator class Titan which was present during all of the major ground assaults towards the end of the Crusade and the beginning of the Horus Heresy. The legendary Dies Irae finally met it's end ten thousand years later during the siege of Hydra Cordatus. Imperator
- Aquila Ignis - Imperator class Titan which attacked Magma City during the start of the schism. Destroyed the last of the Legio Tempestus' Titans, before being destroyed during the destruction of Magma City. Its Hellstorm Cannon was salvaged and transported to Kronus for study, before being lost for 10,000 years. It was finally destroyed during the defense of Victory Bay.
- Death's Head - Warlord Class Titan which fought in the Battle of Davin's Moon during the Great Crusade.
- Ire Incarnatus - Warlord Class Titan. Ancient engine which served the Mechanicum for many long centuries before the Horus Heresy. Badly damaged during the Tarren Suppression, where it's Mars-Pattern head was replaced with a Lucius-pattern.[5a]
- Molossus - Warlord Class Titan
- Phantom Lord - Warlord Class Titan which fought in the Battle of Molech during the Horus Heresy.
- Tellum Ire - Warlord Class Titan
- Black Consul - Reaver Class Titan
- Iron Baron - Reaver Class Titan. Fought in the Battle of Calth alongside the Word Bearers, where it killed 2 lesser and 1 greater enemy Titan engines.[5a]
- Myrmidon Rex - Reaver Class Titan which fought in the Battle of Molech during the Horus Heresy.
- Hand of Ruin - Reaver Class Titan which fought in the Battle of Molech during the Horus Heresy.
- Xestor's Sword - Warlord Class Titan which fought in the Battle of Molech during the Horus Heresy.
- Dread Wake - Reaver Class Titan which fought in the Battle of Molech during the Horus Heresy.
- Ferrum Mori - Reaver Class Titan employed during the Horus Heresy.
- Tenebris Fedelis - Warhound Titan. Commissioned weeks before the outbreak of the Horus Heresy and first saw combat in the Drop Site Massacre.[5a]
- 1: The Horus Heresy Book One - Betrayal, pgs. 138-140
- 2: Imperial Armour 13, pg. 139
- 3: Vengeful Spirit (Novel)[Needs Citation]
- 4: False Gods (Novel)[Needs Citation]
- 5: Adeptus Titanicus (2018) Rulebook pg.58-59
- 5a: pg.80-83