The seven most important Houses are the Noble Houses whose domains extend throughout the Spire, the part of the hive that stretches above the cloud top layer. The Noble Houses are the controllers of the hive’s commerce. They trade far and wide throughout the Imperium and with other hives on Necromunda. The Noble Houses compete against each other for wealth and political power, always seeking to further their own interests at the expense of their rivals. Intrigue and fear of assassination dominate the lives of their ruling families.

The most powerful Noble House is the Imperial or Ruling House of Helmawr. Its domain is the very top part of the Spire, the most desirable territory in the whole hive. Lord Helmawr, the leader of the House, controls the entire planet. He represents the mighty Adeptus Terra of Earth, the governing body of the Imperium of Man.

To the greater universe Lord Helmawr is Necromunda and the planet is his to rule as he pleases. The patriarchs and merchant families of the Noble Houses vie for his attention, and are eager to perform whatever favours are necessary to secure landing and shipping rights, trade licences and tax concessions. Even whilst they curry Lord Helmawr’s favour the Noble Houses scheme behind his back, hoping that one day House Helmawr will be brought low and a new Imperial House will inherit its domain.

The seven Noble Houses of Necromunda are House Helmawr, House Catallus, House Ty, House Ulanti, House Greim, House Ran Lo and House Ko’Iron. These Houses usually don't play a direct part in most of the fighting and exploration of the Underhive, save for the Brat Gangs and the Spyre Hunters.