Tamriel's history has at times supposedly been guided by various secret societies and secretive factions, influencing events and wielding untold power, in every sense of the word. I was wondering if there are any noteworthy examples of such groups that i might not have heard about. There are the Marukhati Selectives of course, which supposedly still exist in some form or another, possibly being the real power behind the Elder Council, or even involving themselves in the Underking's court, Tharnatos or the Red-Dome Templars. Then there are groups like the Psijic Order of Artaeum and the famous Clan Direnni of Balfiera, which supposedly still holds much influence in the Iliac Bay, as well as being the keepers of the Direnni Tower.

Temple Zero Society

Don't know if we could call entities like the Elder Council or Clan Direnni secret societies. Tiber's vision of the Blades sort of fits the bill. Actually, if the Greybeards are to be believed, they might still sort of be one if the "they have never truly served the Dragonborn" line means anything.

Other then that, the Mythic Dawn is the other noteworthy example I can think of off the top of my head.

Surely no truly secret society can ever have been heard of by outsiders, by definition.

Unless it's an illuminati situation, where it actually existed for a very short period of time out in the open as a private club of gentlemen who share similar free-mason views and then was disbanded, yet according to conspiracy crazies still exists in secrecy doing all kinds of world defining stuff such as organizing the Bilderberg meetings where the world is divided amongst their powerful members and the future world-defining events are being planned. (I don't support these speculations, just to be clear)

But it's an idea for a legendary lore such as that of Tamriel.

Oh, clearly Tamriel's history is predominantly written by conspiracy theorists. That's the only explanation. Insecurity generally abounds when the jungles and gods keep disappearing every few centuries. Tamriel has a consistent issue with genuine mystery cults being mistaken for yet more gangs of lunatics with printing presses.

I wonder if there might be a secret society of sorts in Hammerfell. Divided by the Crowns and the Forbears, there could have been a group, or more probably, groups, that operated beyond the bounds of their factions for one reason or another. Aside from the Forbears and the Crowns, there are the Lhotunics, a largely irrelevant group that attempted to bridge the gap, and the Alik'r nomadic tribes, and of course, the Devotees of Satakal, worshipers of the old Yokudan god of creation and destruction. Terrorising the countryside in the old Ra'Gada fashion, causing no end of strife for the Alik'r border-states, and performing terrible exhibitions of "shedding their own skin", the Satakals are not to be triffeled with.

Now, that description, along with Galathil the Face Sculptor's comments about being thought by the "Hollow-Faced Men of Nohotogrha", Nohotogrha Oasis being mentioned as being a place connected to the Satakals in the PGE1, and later texts introduced in ESO stating that it was Satakal that destroyed Yokuda, caused by power-hungry Ansei summoning fell things and performing forbidden rituals, really makes me think there might be something going on with the Devotees of Satakal in Hammerfell. What exactly could "shedding their skin" mean? It could mean a ritualistic form of flaying, or perhaps a form of illusion magic, performed b the Hollow-Faced Men, perhaps both. Now that is a conspiracy theory.