The Thargoids are an alien insectoid species who are said to originate outside of known space, perhaps existing in a parallel universe or spatial dimension. They are one of the two known living sapient species in the Milky Way galaxy (the other being humans), although ruins and artefacts of other species have been found and much of the galaxy remains unexplored. Thargoids are reputed to be highly defensive and seemingly rebuff all diplomatic overtures with unmitigated hostility.