The Deathshroud were the elite Space Marines of the Death Guard Legion who served as the Primarch Mortarion's mute Honour Guard during the Great Crusade and Horus Heresy. Great secrecy surrounded this elite cadre. Their numbers were chosen from amongst the ranks of the Death Guard Legion and each member was singled out and personally selected by their Primarch for the bravery and valour they had displayed in combat. Once chosen, the selected Battle-Brother would foreswear his former life as a common rank-and-file Astartes of the XIV Legion, and would swear binding oaths of secrecy as a new member of the secretive Deathshroud. Each member of the Deathshroud would be listed as killed in action to allay any suspicions as to their true identity, and they would forever conceal their faces behind heavy enclosed helmets, masks or hoods. Each Deathshroud Astartes' identity was known only to their Primarch himself, even after their deaths.
The Deathshroud wore Artificer-crafted Cataphractii Pattern Terminator Armour of the highest quality, which presented a foreboding appearance. Like their Primarch, each member of the Deathshroud wielded a large Power Scythe known as a Manreaper. It was the Deathshroud's sacred duty to never stray more than forty-nine paces from Mortarion. Two Deathshroud guardians customarily escorted the Primarch at any given time, though there may have been more hidden in the shadows. These stoic warriors' presence was quite intimidating as when not in motion they would stand uniformly at attention, still as statues. But in battle they were equally frightening, for whatever the odds, they always moved inexorably towards their target, as unerring as the automated killing machines employed by the Legio Cybernetica. Their fate after the end of the Horus Heresy remains unknown.
- Horus Heresy: Collected Visions, pg. 229
- Flight of the Eisenstein (Novel) by James Swallow, pp. 19-20, 30, 57, 59, 67, 72