The Hrud are a secretive and little-understood xenos species, nocturnal creatures that dwell in darkness and shun the light of the wider galaxy. Sightings describe hunched, shrouded figures wreathed in shadow, and so elusive are they that much of what the Imperium believes about them is guesswork and superstition.
What makes the Hrud truly dangerous is the strange entropic field they generate. Simply by their presence, the Hrud accelerate the decay of everything around them: metal corrodes, stone crumbles, and living beings age and wither with unnatural speed. A large enough gathering can rot a fortress to dust and turn its defenders into aged husks, making them a creeping menace wherever they infest a world's underlevels and tunnels.
The Hrud are a migratory people, and periodically vast numbers of them surge out of their warrens in great migrations that can undermine and devastate entire regions. Imperial forces, including the Astra Militarum, have fought bitter subterranean campaigns to purge them, while the Ordo Xenos of the Inquisition studies them warily, seeking to understand a species that seems to embody entropy itself. For all the fear they inspire, the Hrud remain one of the galaxy's abiding mysteries, glimpsed far more often than they are truly known.