Iconian

The Iconians were a highly advanced race of beings from the planet Iconia in the Romulan Neutral zone.

Background
Very little is known of the Iconians, other than they were called Demons of Air and Darkness and that they "invaded" other worlds through advanced technology. This has since been disproven.

The Iconians were proberly the most advanced beings ever to inhabit the galaxy.

The Iconian/Iccobar War
Around 10,000 years ago, the Iconians went to war with a local race called the Iccobar. Despite being technologically advanced, the Iconians could not end the war. While they could win almost every battle, they could find no way to end the conflict, despite attempts at doomsday weapons or sneak strikes. Then, one day, after several years at war, the Iconians realised that they would lose, and built ten Dyson spheres where the technology and species could survive.

The Iconian Stargates
There is solid evidence that the Iconians constructed the advanced Stargates that Starfleet use today for covert operations. Although Federation science has a solid and advanced understanding of the gates, the real "engine" of the wormholes and the gates remains unknown.

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======================================== Then, they fled, and became galactic refugees. Having being almost wiped out by the Iccobar, the Iconians were few and scattered. They attempted unsuccessfully to rebuild their race, and over time, lost their god-like abilities, and became no more than space refugees. Satisfied, the Iccobar turned their attention towards the Omega project, a plan that would harness the energy from a dimensional vortex to generate almost unlimited power. This project would take millions of years, and so, the Iccobar slept, waiting for the day when they could rule the stars. The Iconians (now the Idrill) became a secondary race to the Attrexians, and almost slaves to them.

All over the galaxy, remnants of the Iconians are left. Temples, murals, and of course, the Stargates. The Iccobar, however are in a deep sleep, in the Azure nebula, awaiting completion of the Omega project. Their technology, ships, all that was once Iconian is now ready for Iccobar masters to take control. The Idrill and the Iconians/Iccobar are related, and thus use the same ships.