Societies hidden from normal mankind, organizations even entire cultures existing beneath the common experience of normal society. These are staples in many genres of fiction from fantasy (most sub-genres) to mystery, action to sci-fi. And whenever they appear, some worldbuilding is involved.
The very fact of the existence of hidden societies in a text is worldbuilding. Yes, we have hidden societies in the real world, some more hidden than others – the collegiate greek organizations to the sort of gentlemens’ clubs that have smoking parlors (and no dancers). But the ones in works of fiction are almost exclusively fictitious societies, the creation of the author. Because of the nature of most such societies, the author has to create a world in which hidden societies of a given type can exist and are indeed assumed to exist.
Four major types of hidden society come to mind immediately:
Government Agencies — Whether Jason Bourne’s Treadstone or The Brotherhood of the Rose, the British Secret Service or IM Teams, whether James Patterson or David Morrell, Ian Fleming or someone else, action novels, shows, and movies are filled with top secret government agencies, many of which not even the heads of state are aware of. These agencies are often tasked with assassination, intelligence gathering, or other high stakes missions during which they must maintain a (relatively) low profile for political or other reasons. And we know from a wide range of sources that this sort of organization is not how real world intelligence agencies work, for a variety of reasons (including technology – Bond, Ethan Hunt).
Criminal Organizations — Secret criminal organizations are common fodder as well. From SMERSH to Moriarty to HYDRA, secret criminals and criminal societies are everywhere. Ian Fleming and Arthur Conan Doyle created theirs precisely to have a core villain for their respective heroes, and Fleming’s has the added bonus of existing after the Soviet specter died with the Cold War. Marvel comics created their’s, I think, to balance the teams of heroes. It also makes sense that if superheroes band together, supervillains would do so in response.
Secret Societies — The staple of conspiracy thrillers, secret societies add an element of clandestine fear to a story. Whether David Morrell’s society of Merovingian descendants or assassins hunting the Church’s enemies or David Brown’s sinister Catholic sub-organizations, they give readers the sense of accessing some hidden threat. They also give the protagonists a way to kill with impunity, because they’re saving normal society from the hidden threat.
Hidden Magic — Everyone in the world who hasn’t been living under a rock for the last two decades knows about J.K. Rowling’s hidden societies of wizards and witches. Other examples include Tanya Huff’s hidden witch family (The Enchantment Emporium) and Rick Riordan’s hidden societies of Greek demigods, Roman demigods, and Egyptian magicians. In each case, the concealment comes in part from fear – of being hunted, exploited, or bothered, or something else – in large part. But, being hidden also keeps them apart from modern life (except Huff’s) via technology among other things.
What do hidden societies need for their existence?
First, a world in which their existence is assumed (by the writer and the reader). After that, they need a way to remain concealed. This can be the fog that hides Riordan’s demigods from normal mortals to control of some supertechnology to global influence over governments and corporations. How they remain hidden is especially important in contemporary and sci-fi settings as it becomes more difficult to conceal things due to the prevalence of information technology (e.g. camera and video phones, cctv, the interwebs).
Bonus things a hidden society could use include some means of funding (MiB’s patents on velcro, etc.; Treadstone’s federal CIA funding; HYDRA’s crime sprees), facilities, equipment, and transportation (after all, in a post-2001 world, it has become rather difficult to transport weaponry across national borders in many cases, not impossible though).