In an attempt to gain world destroying technology, the Snarks have been at war with the alien Kymellians for millenia. When a Kymellian gave Power Pack their powers, the Snarks kept attempting to kidnap them and gain their powers.
The Snarks (or Zn'rx) first came to Earth to retrieve the Antimatter device begin designed by Earth scientist, James Power. The Snarks ran into Aelfyre Whitemane, who was mortally injured in the battle that took place. The Snarks searched for and eventually found Dr. Power and stole away with him and his "mate" to pull the design for the Antimatter device from his head. The Snarks plans were foiled by the Power Pack after they obtained the powers of the Four Fundamental Forces.
The Snarks ultimate downfall was the fact that they have no imagination. Young Katie Power of the Power Pack led the Snark Queen Mother, Maraud, to believe that her mission was to spread love throughout the universe, rather than destroy it.
Zn'rx is there real name, but that was unpronounceable for humans. Julie Power gave them the name "Snarks" after the creatures in The Hunting of the Snark by Lewis Caroll.
Snarks stand eight feet tall, weigh 400lbs, have red eyes and green scales. They are larger and stronger than humans and also live longer. Like Earth reptiles, Snarks are cold blooded and are vulnerable to cold tempuratures.
Snarks are undyingly loyal to their Queen Mother, Maraud, as it is her who supplies the Royal Nectar. Snarks, raised on the nectar, have a special craving for it and will do anything for it. Using this, Maraud rewards her followers with nectar and punishes those who fail her by revoking it.