From Wikipedia:
An Egregore (also spelled egregor; from French égrégore, from Ancient Greek ἐγρήγορος, egrēgoros 'wakeful') is a concept in Western esotericism of a non-physical entity or thoughtform that arises from the collective thoughts and emotions of a distinct group of individuals.
Adapted by the rationalists from an older esoteric term for a spirit made of a group's thoughts, an egregore is a collective (of persons) that seems to act like a being in its own right, like "America" or "Microsoft", although one need not be legally recognized to qualify. They often don't act in the best interest of individual persons, including their own members, analogous to predators or parasites.
Egregores don't need to have well-defined "members". Generally, they are programs that run on groups of people and have some level of self-persistence. Moloch, for instance, is an egregore consisting of all failures of coordination, and so it runs on almost all humans but does not fully envelop any of them.
It's unclear to what extent these entities can be called "minds" (or "conscious"), but your own mind is also made up of a collective (of neurons). "In truth, there are only atoms and the void," and yet we give names to higher-order structures, like individuals or countries.
See also: memetics, reductionism, eldrich analogies, moral mazes.