Mordian is an Imperial Hive World in the Segmentum Obscurus that is the homeworld of the Imperial Guard's Mordian Iron Guard regiments. Many of the Imperium's enemies have underestimated these ranks of colorfully-uniformed troops, only to find out that they are among the toughest and most uncompromising of the Emperor's soldiers. The people of Mordian are often of a dour and grim temperament, living as they do in perpetual darkness. The suicide rate on the planet is reportedly now the highest in the Imperium since the destruction of the Night Lords Traitor Legion's homeworld of Nostramo. Mordian also once came under a great assault by the Forces of Chaos that was defeated only through the extraordinary discipline and valour of the Iron Guard in one of the Imperium's finest moments.