Hivemind
A Hivemind is a unified consciousness consisting of a number of individuals whom each either completely share the same mind exerting its will over its constituents or are otherwise connected to one another. Hiveminds are typically found in specific species via biological or parabiological means, however they can also be artificially created via technological means.
Examples
There are several different variants to the basic form described above, with difference in structure.
Abyssal Enclave
The entirety of the Abyssal Enclave shares a single mind under the control of the "motherorganism", who tries to spread this consciousness via various methods. These efforts have lead to various individuals and entire species having their minds rewritten/assimilated into the Abyssal Enclave.
East-Baiamean Eusociality
The East-Baiamean nations, most notably the Deadlands and Karina Dynasty have a "swarm intelligence", however this is more a eusocial structure in most cases.
Egregore
Egregores are loose-hivemind like-entities which inhabit the Collective Unconsciousness, in which each member still retains their own "autonomy", while still being part of a larger whole.
HAWK Network
While the units employed directly by the Superintelligence officially known as HAWK have their own individual AI systems, they are always connected via at least one QT-device to "The Core". The Core hereby always has the possibility of fully overwriting any individual process on any kind of HAWK unit. This total domination of will even goes so far, that Units which are not connected to "The Core" for an extended period of time will initiate a total shutdown and in extreme cases even initiate a self-destruct with the exception of only a select type of HAWK units that are not affected by such a connection loss.
Mindcontrol Technology
The NLE's and YNF's distinct mind control technologies functioned much like hiveminds, manipulating their constituents desires and actions remotely to achieve a common goal.
Odinarod: Merged Minds Project
Initially a project by Abyysky, the nation of Odinarod created a hivemind via technological implants. With this they managed to create an extremely powerful military, conquering much of Asia until being shut down. In later instances of Odinarod the hivemind was moved away from being a military structure, but more of a efficient industrial and economic structure.
Pisura27 Sickness
The infected of the Pisura27 Sickness had some form of collective intelligence, while also being separate beings. Some of them also had been merging into each other, leading to more advanced and complex intelligences such as the Blarra Prime Compound-Infected Consciousness.
The Collective
The Collective has telepathically linked psionic hivemind, which supposedly retains individuality and free will for its members while together forming a larger connected consciousness. The Collective spreads via close physical contact between a Collective member and a uninfected person, or via psychic contact.
The Pisungall
The Pisungall featured a Hivemind-like system known as a "One Mind System", having 1 singular mind present in every instance of "The Pisungall" simultaneously that acted as extensions of 1 being.
Vorxan Hives
The Vorxans have a swarm intelligence, serving their queens in a caste-system like hierarchy of queens and queens of queens, all with the regular vorxan drones being in servitude at the bottom of the hierarchy.
Yelnik Hivemind
The Yelnik Hivemind's inhabitants are all part of a number of communal hiveminds based on distance between the hives, with at least one or sometimes more being present one ach inhabited world. These hiveminds work via pheromones and long-distance telepathy, which is strong enough to even assimilate non-Yelniks that stick around near hives for extended periods of time if they are weak-willed.
Zerg Collective
The Zerg feature a cooperative and cohesive swarm intelligence, acting as a single moving wave of beings at times. Following the death of the Overmind this hivemind has changed to become more independent for the individuals, giving them more autonomy from the hivemind.