- Kaylon 1 (Kaylons): Though not a member world and despite their sense of superiority to humanoid life, Kaylon is on friendly terms with the Union to the point that they have assigned a representative to serve on a Union vessel in order to study human behavior.
- Calivon: Recognizing their great technological advantage and resulting sense of superiority, the Union are wary of the Calivon to the point of declaring their space off-limits, wishing to avoid any engagements.
- Krill (Krill): Taught by their Ankhana that they are superior to all other life and despising humans especially, the Krill have attacked several Union colonies leading to engagements with the Union fleet. However, a state of war is yet to be declared.
- Navarians & Bruidians: These two powers were engaged in a long dispute focused on a planet at the Union border. Seeking to prevent war breaking out and affecting neighbouring worlds, the Union served as neutral mediators to foster peace.
Within the Planetary Union, there are five Divisions, or Crew Ranks:
The admirals use a golden insignia of the Planetary Union with a purple uniform.
The commanders and executives use a silver insignia of the Planetary Union with a blue uniform.
Commanders are the heads of Union ships. Executives include the first officer and second officer under the ship's commander.
The scientists use an insignia of an atom-like emblem with a green uniform. Scientists specializing in medical care however use an insignia of a green cross surrounding an atom.
The engineers use an insignia of engine gears with an orange uniform.
The security personnel use an insignia of wings over a shield with a red uniform.
The ranks within the Planetary Union fleet signify a crew member's status. Their insignia are worn on the shoulders of the uniform. Junior and senior officers have silver insignias, while flag officers have gold insignias:
- One bar, silver - ensign
- Two bars, silver - lieutenant
- Three bars (thinner central bar), silver - lieutenant commander
- Three bars, silver - commander
- Four bars, silver, with ships name in a darker band forward of the bars - captain
- Stars in a circle, gold - admiral
Planetary Union spaceships are named after aviation and space pioneers from Earth.
- USS Blériot named after Louis Blériot.
- USS Chanute named after Octave Chanute.
- USS Druyan named after Ann Druyan.
- USS Olympia
- USS Orville (ECV-197) named after Orville Wright.