Stygians
Stygian - A race of incredibly vile and cruel shadow-like humanoids which originate in another dimension once used by the Avians for long-distance travel. They seem to absorb light, rather than reflect it, making them appear as black silhouettes of their true forms in our dimension - except for their eyes, which burn with a stark white light that appears to "smoke". Some of their kind feature aspects of their foul god, the Viscera queen, such as insect-like pincers and deadly spines. The Stygian are free to terrorize our own dimension, thanks to the still-active portals located on the lost Avian home worlds.