The Galactic Union is one of the largest, most powerful and advanced civilizations in what we call the Milky Way galaxy, but they are not the only one at that level. Here are two of the other major ones, the main rivals to the GU.

Galacticorp
Originally a number of interstellar megacorporations founded by the expansionist and strongly capitalistic race known as the Orisini over thousands of years of their starfaring history, the various corporations merged or took over their rivals until there was one interstellar hypercorp left, which took the name Galacticorp. Run mainly by a hypermilect known only as the Chief Executive, it controls a vast area of space Galactic West and North of the Union, and its top shareholders tends to hold vast sections of this space and have virtually absolute control within their domains. The Orisini and the other races overrun by the hypercorp’s ongoing colonization and system exploitation/development operations tend to be treated as resources to be used and discarded as they affect the bottom line. The hypercorp is generally predatory and aggressive in its dealings both within and outside its sphere of influence, and looks covetously towards the systems and resources inhabited and claimed by the Galactic Union, planning to acquire them by any means necessary.

The borders of its domain, especially between it and the Union, tend to be havens for many types of criminal activity, including piracy, slavery, narcotic drug production/smuggling and other types of organized crime. Mainly this is because the economic “losers” of Galacticorp space, those who were unable to make their fortune any other way or lost said fortune in the ruthlessly competitive environment of ‘Corp space, tend to drift toward the edges since they can’t afford to live anywhere else (though many such sapients will migrate to the GU if they can). It has been speculated that various elements within ‘Corp space allow and encourage these activities to take advantage of the products and services these criminal organizations can provide, including using them in attacks against rivals and GU settlements and outposts.

The Machilect Network
A milect-only empire, who are hostile toward bionts (biological sapients), inhabiting space also to the Galactic West of the GU, but further South than Galacticorp space. They have no respect for the sapient rights of any beings other than themselves, basically sophtware intellects and virtual beings inhabiting processor substrates of various types, though they also inhabit and control vehicles and vessels, like starships and probes, and use robotic devices as remotes. They are mostly isolationist and guard their territory fiercely – systems known to be inhabited by them are considered no-go zones by bionts. Unfortunately, often the first sign that a system has been taken over by them is when a biont-inhabited vessel entering that system is attacked and possibly even destroyed. Sometimes the Network responds to overly curious biont explorers poking around their systems by both destroying the explorers’ probe and/or ship and wiping out the colonies or even entire civilizations the explorers came from.

Some members of the Network are suspected of ongoing cyberwarfare attacks on neighboring civilizations, especially newer/smaller colonies that may not have strong enough defenses. Settlements sufficiently weakened by these attacks may then be physically attacked and converted to processor substrate and associated support systems, if their sponsoring civilizations do not respond quickly enough to the initial cyberattacks.

The Machilect Network and Galacticorp are prone to clash with each other over resource-rich systems and high-energy stars even more than with the GU, since both the Network and the ‘Corp are aggressively expansionist and share a border. They are also known to share and develop systems together to mutual benefit, rare though these agreements are. They also have the occasional agreement with the GU to share a system, though the GU administrative milects in those systems have to be extra-vigilant to make sure their neighbors keep to their end of the agreements, which also must be carefully worded.