Ekosian spacecraft were a type of 23rd century spaceship used by the Ekosian civilization of the planet Ekos for inter-system travel at M43 Alpha, from circa the 2260s decade.
History and specifications[]
The Ekosians were barely industrialized before their development was contaminated by a Prime Directive violation by Federation observer John Gill, and as such, much of the technology required for them to create these vessels was stolen from nearby Zeos. The Nazi Party of Ekos manufactured a fleet of these craft for their genocidal "Final Solution", where all Zeons would be expelled from Ekos and an invasion of their neighboring homeworld would follow. The Zeon resistance had placed many spies aboard this fleet to sabotage the operation. (TOS episode & Star Trek 12 novelization: Patterns of Force)
Appendices[]
Background[]

Star Trek 12 ship.
While these ships remained unseen in the original and remastered episodes they were mentioned in, the first edition of Star Trek 12, which contained the novelization of "Patterns of Force", had the USS Enterprise depicted orbiting a planet and sighting another spacecraft. Of the five stories contained in that volume, the "Patterns of Force" Ekosian ship is the most likely candidate for what vessel is represented. The cover art is widely attributed to series cover artist Eddie Jones, but there is no signature or credit given for the art in the volume, and there is no version available where the ship is not obscured by text.