Skrel

The Skrel (a name coined by Humans, as their real name is unknown) are a mysterious, unseen race of spacefaring aliens which have been responsible for the creation of the Ursa in an attempt to exterminate Human settlers from the world of Nova Prime; which seems to be regarded as a sacred holy land by the Skrel, even though, as far as it's known, the planet has never been inhabited before Human arrival.