Stuff like Freemasons and other real non-illuminati organizations that are the center of conspiracy theories count too right?
Topic on Talk:The Illuminati
Other conspiratorial groups are The Conspiracy, possibly even the Ancient Conspiracy.
This page is Illuminati-only, as far as I can tell.
I was asking because Tropes Are Flexible and the laconic suggested to me that it could be more broad. I just looked at the pages you mentioned and none of them have an explicit requirement of being a (potentially disbanded or destroyed) real life organization.