The Eudaimonia Foundation
Size:
Population: Aprox 90 Trillion
Planets: Aprox 7,000 (and decreasing as evacuations and transfers to city-ships is ongoing)
City-Ships: 3,000,000+
Species: Assorted species, AI's, trans-species entities. Present fashion of form is Terran-humanoid.
Its difficult to classify the Eudaimonia Foundation by any one majority species, due to both the diversity of member races and the proliferation of body resleeving technology allowing persons to remote-control or transfer into new bodies on a regular basis. The present "popular fashion" of form in the universe's dying age are humanoid bodies, which most of the Foundation has adopted over the past 2,000 years and intend to see the end of the universe with.
Culture
The Eudaimonia Foundation is all about pleasure and self-fulfillment, insofar as you respect others rights to self-fulfillment and "live and let live". There are very few written laws in the Foundation, although some planets and city-ships may have their own set of rules as part of a "theme" that are mostly voluntary, but a large number of unwritten social norms and people can live elsewhere if they don't like them. Even death and murder arn't much of an issue on some planets due to active backups and respawns, although its usually not socially acceptable to kill outside of designated regions. But in general, crime in the Foundation is for all intents and purposes non existent as near post-scarcity enables good life for anyone for nothing, and mostly kept to the edges of the Foundation in interaction with other species.
In short, the whole of the Foundation is in a state of permanent vacation. Their near post-scarcity society is run by near-indestructible automated systems that see to every basic need of their creators, and more than a few of their luxuries, and the greatest challenge for any Eudaimonian is to make effective use of their free time. However in order to obtain higher status and luxury, a Eudaimonian has to contribute to the Foundation in a cultural manner, although this is more of a societal expectation rather than a hard hierarchical limit. Exploration, discovery, roleplay, creative arts, and diplomacy are common methods of earning berths on fancier city-ships or getting into parties.
Many worlds and city-ships adopt a "theme" its denizens are recommended to adopt and try out as part of their "rent" for living in luxury, which Eudaimonians consider a pleasant way to add variety to their lives. Some noted examples include a ocean planet hosts itself as a post-post-apocalypse world filled with ruins and adventure amidst the archipelagos, while one city-ship hosts games and entertainment in the guise of an ancient medieval empire with gladiator games and feudal arts, while another city-ship obligates everyone to wear a customized suit of powered armor and has no other rules than that.
Military
The Foundation doesn't possess a standing military, as they have very little need for one. The usual mechanisms and desires behind conquest and imperialism are nonexistant amongst the Foundation, and they would rather have other species join them peacefully or not at all. Live and let live. The Foundation will never start a war.
However, that isn't to say the Foundation is inept at war. Mothball yards of thousands of battleships and battlecruisers from pre-Foundation navies are still maintained, and the same nanotech industry that sustains their post-scarcity lifestyles can be easily converted over to large-scale war industry if absolutely needed. Graviton and antimatter warheads, positron beams, and hyperkinetic railguns firing "fun stuff" are common weapons, while every Foundation ship is equipped with klein-bottle shields that redirect incoming fire onto itself and outwards, providing a powerful defense that while not invincible and can be saturated, is still extremely potent.
However any military effort would be hampered by a lack of manpower and support. While the AI's certainly can run an entire war on their own and the explorer groups can certainly serve as special forces units if needed, unless a exceedingly pressing casus belli is given, any military action will be limited to a handful of volunteers. In terms of material factors, only the city-ships closest to any warzone or predicted warzone will industrialize for war and demothball local warship yards. Support from outside a given sector is rare, and the possibility of the Foundation adopting a total-war mentality as a whole is nonexistant.
But by and large, the Foundation doesn't want to go to war, and its so large and powerful that its not worth conquering for conventional reasons. Although the Foundation's plans to build extra-galactic starships may be a issue for jealous neighbors.
Notes: While the Foundation seems massive and huge, the bulk of it won't even care about interstellar affairs and is effectively a non-entity in outside wars and conflicts. And even then, it will take a serious amount of provocation to rouse any of the central sectors and the oldest and most powerful city-ships. Most of the time, only the rim and frontier city-ships and worlds will be the active elements of the Foundation in the dying stars interacting with other societies.