Barghesi
The Barghesi are a xenos species living in the Eastern Fringe of the galaxy, on a region known as the Grendl Stars (a particularly unimportant area of realspace, mostly known as Sanguinius' wings, because that's the shape the planets' distribution take). This xeno is well known in the galaxy due to its unusual strenghts, brutality and aggressiveness. The White Scars and Iron Lords have fought this aliens in multiple occasions, as well as the Emperor's Children, and they have always proved to be a considerably tough opponent to be. Dark Eldar usually capture them as a special show for their gladiatorial arenas, their bloodlust always a massive spectacle. Their fame has reached a point that many inquisitors of the Ordo Xenos are trying to exterminate this species to avoid the tyranid fleets near the Grendl Stars to absorb their DNA and become an even more dangerous threat.