These are recognized ruling bodies, commonly considered to be the authority over what ever space they consider theirs.
These are groups that don't have space, but are powerful enough to be worth noting.
Exploration Guilds emerged at almost the same time as the first human-made subspace ships rolled out of dry dock. They are a natural expression of the human desires to explore and expand, and it was their hard work and sacrifices that paved the way for humanity's galactic growth. In the spirit of cooperation, they offered their services to the Terran Republic after Second Contact as well and surprisingly, the Republic often made use of their services for systems that lay outside their claimed boundaries.
It did not take long for these guilds to welcome members of both the Lyndri and the NorAellians into their ranks, becoming a more united exploration effort than a strictly human venture. This also meant opening up their services to the Lyndri and NorAellian governments, though neither really took them up on the offer. The NorAellians laughed, and then warned them off from the area behind the Wall.
Over the centuries, many of these guilds vanished, either through attrition, or mergers with other guilds, or by being incorporated into a human government. Today, only a handful remain active in their pursuit of the human dream of unfettered exploration.
Seekers of the Silver Wing - Originally known as the Seekers of Orion, this exploration guild became more religion than guild after an encounter with a unique hallucinogen. They still operate as an exploration guild, in that they still explore new and uncharted systems and sell the claims on them to interested parties, but they are no longer driven by pure exploration. They are actively looking for a specific paradise world that they believe they have been promised.
Second Star Guild - DEFUNCT- Named for the line from Peter Pan about how to get to Neverland: "Second star to the right, and straight on 'til morning." For awhile, that was their way of selecting where to explore next: They'd pick a star, count two visible stars to the right of it (relative to their position), and go that way. This was, as you might imagine, a bad way of selecting a destination, and Second Star suffered a far higher number of lost ships than any other guild in those early days. Eventually, they learned and their greatest lasting contribution was in developing the first human engineered subspace navigational algorithms.
Neo Argonauts - DEFUNCT - Named both for the Greek myth and the constellation inspired by it, the Neo Argonauts became obsessive about their ships and their crews, to such a degree that "Argo Mania" became a recognized term amongst mental health professionals who worked with ship crews. One of the last Neo Argonaut ships stumbled onto the system that plays host to the dying star that became home to the Canticle of Dead Light, and it's widely rumored that it was the crew of this last Argo class, Argo XXIII, that became the founders of the death cult, though this is unconfirmed.
The Venture Society - This guild modeled themselves on the old explorer societies of the ancient Victorian Era. They attempted to cast themselves as the heirs to those societies: noble explorers seeking to fill in the blank spots on the map and return with stories and artifacts. The Venture Society station in orbit around one of the moons of New Corinth is more of a museum than social club, though there are parts of the station reserved only for Venture members and their guests. Supposedly, the galas they throw every five years are legendary, but you have to be a crew member, a guest of a crew member, or insanely wealthy to warrant an invitation. Walker d'Ardenne attends every chance he gets, though his crewmate Mikhail is no longer welcome after the Great Dane incident.
Polaris Co. - Folded into the League - One of the only guilds who fully embraced their true corporate nature. They had a registered headquarters on Calysto, a Board of Trustees, a CEO, even an entire org chart. They presented themselves as more guided by profit than by pure exploration. It should come as little shock that this guild was bought out by the League and incorporated into the government as their official exploration arm. The Polaris Scouting and Exploration unit is still in service today, though their last notable find was the Corona Noir Ki system that is now home to the institute of the same name.
Faxian Jituan - Folded into the Republic - The only guild that held a license from the Terran Republic to explore and chart new systems within their borders. It should come as little shock that they did not operate as an independent guild for very long before they were folded into the Republic military structure. Much like Polaris, they retained their name, and are still an operational unit to this day. Their greatest claim to fame was the discovery of the Arkaroo system which opened up the fifth and final Republic sector for colonization and exploration.
Drake's Heirs - This guild was established on a claim of direct lineage from the legendary explorer and pirate from the age of sail back on Earth. While this claim was never proven, and was often called into doubt over the years, the guild itself flourished. Many have suggested that this was because, quite like their namesake, the guild was not above a bit of piracy amongst their explorations. The guild now operates out of an old ore refinery rig in a played out system in Freelance space. The refinery was renamed to Golden Hind in honor of Drake's ship, and the guild has been adding to and modifying the rig ever since.
Starlight Wanderers - Perhaps the last of the exploration guilds still dedicated to the pure adventure of it all, still driven by the desire to explore and discover and find something new, rather than be motivated by religious fervor, or fame and glory, or pure profit, or patriotic duty. The Wanderers just want to see what's out there. For the last century, they had been falling on harder and harder times until the last two dozen ships gathered together and cut a deal with CNK for a new fleet of top of the line ships: the Waypoint class. Now, the guild seems to have a new lease on life.
These are groups that are not officially recognized, and most people either don't know about them or have only heard wild rumors or conspiracy theories.