The Imperial Houses are the nobility of the Holy Terran Empire. They rule entire solar systems, or large portions thereof, and usually consist of one extended family of blood relatives and their various cadet branches of close friends and relatives-by-adoption. This gives them enough family members to effectively spit up an entire planet or two into large fiefdoms and personal domains.
This category page lists all the Imperial Houses for which was have detailed articles so far. The internal details of the other houses are, for the time being, being left vague so future story writers can fill in the blanks with whatever details are needed to make their planned storylines work.