Star Trek Ascendancy - Breen Confederacy

Little is known about the secretive Breen, not their appearance, and not even whether they are a single species or several species working together. Intensely territorial, the Breen annihilated the Klingon fleet sent to conquer them, leaving the Klingons no wiser as to who or even what they were facing. As the Romulans say, “Never turn your back on a Breen.”