Some of them anyway.
A mysterious species by @The-Wizard-of-Zaar (The Wizard Of Zaar)
A diabolical and utterly predatory species, invading vulnerable ships out in the wilder parts of space.
Few have survived attacks by this species, none have ever ascertained the name or Homeworld of this monstrous race. Nor are they associated with any particular region of the known galaxy; seemingly attacking everywhere and anywhere a lone, outwardly defenceless ship is unlucky enough to catch their eye.
However those who have survived their attacks often have done so through extraordinary feats of escape or have braved fierce conflicts against them and managed to repel them. What is known are descriptions and recorded footage of these beings, and that their goal evidently is to take live captives or harvest their organs on the spot.
The militaries, pirates and adventurers of many a species have gone out seeking to find and confront this species... To no avail.
You don't find them, they find you.
these are the scary guys