Orion was a name given to the star system that contained the homeworld of the Orion race. (TAS novelization: The Time Trap)

It is unclear which system "Orion" actually is. Television and TAS novelization sources refer to 'Orion' either as a system or in the context of a planet, or in more vague terms, and imply that this Orion is the home of the Orion race. They also give an Orion I and Orion III, implying a star called Orion. However, in real-world astronomy, there is no such star, only the Orion constellation (stars of this constellation are named "Orionis" however).

However, many other sources have developed the Rigel system, Beta Orionis, as the home of the Orions, with either Rigel VII and Rigel VIII both developed as their homeworld, each also named "Orion". The Decipher RPG module: Worlds calls both Rigel VII and the star Rigel "Kolar", the Orion word for "Orion", suggesting that Rigel is the so-called Orion system. On the other hand, the ST reference: Star Charts names the Pi-3 Orionis system "Orion", perhaps suggesting that the Orion homeworld is there.

This article collects references to "Orion" as a star system that cannot be fully placed elsewhere. Please see Rigel system and Pi-3 Orionis for more information, and please also see Orion (planet) for references to Orion as a planet.

It was a small system but contained three inhabited worlds. (TAS novelization: The Pirates of Orion)

The TAS novelization: The Pirates of Orion doesn't name the system or the worlds. The title "...of Orion" implies this name.

Orion was well-known for its dances. Devna, an Orionite trapped in Elysia and serving as Interpreter of Laws for the Elysian Council, longed to see Orion again. She declined Kirk's offer to return, however, having accepted her place in Elysia. (TAS episode & novelization: The Time Trap)

In the late 24th century, it was possible to obtain an unlisted bank account in the Orion system. Quark once wished he'd kept more of his money in one. (DS9 novel: Devil in the Sky)

The worlds of the Orion system might be the origin of the Orion wing-slug (TNG episode: "Ménage à Troi", Decipher RPG module: Creatures, TOS - My Brother's Keeper novel: Constitution, DS9 novel: Wrath of the Prophets), the Orion spine boar (ST novel: Excelsior: Forged in Fire), the Orion emerald finch (Decipher RPG module: Creatures), and the Orion fern tree. (TOS novel: Traitor Winds)

It is unclear where these plants and animals come from, only that they are named 'Orion', implying an origin or a familiarity with this system or with the Orion people.