An interstellar trade guild charged with the construction and maintenance of star-gates by means of exotic matter. The true name of their representative in our Solar system is unknown, but humans have taken the name of the profession as a proper noun, calling this being the Starspanner.
Like all Guilds, the Starspanners are secretive and have cloaked their expertise in a certain amount of mystical grandeur.
For reasons that are difficult to explain (meaning that it's late and I don't quite understand the science), being able to travel faster-than-light, such as via a star-gate, necessarily involves time travel, with an attendant risk of logical paradoxes. "Cause Must Precede Effect" is the Guild's core ethical principle: gates must never be opened to societies barbaric enough to create paradox. As part of its mandate, the Starspanner Guild maintains an ferocious inquisition against unsanctioned time travelers.
(In physics lingo, I'm goofing around and saying that the Starspanner Guild is a sentient, organized, institutional form of "consistency protection.")