Nivawk was a large, hawk-like Rahi of an unknown species. However, it was not a dangerous predator. Instead of hunting, it would scavenge for food, making it like a robotic vulture. When Makuta came to Metru Nui to pose as it's leader, Turaga Dume, he used Nivawk to spy on his enemies. During the Great Cataclysm, Makuta absorbed Nivawk, along with Nidhiki and Krekka into his essence, so he could shapeshift into a more powerful form.
Role in the series
Nivawk didn't became a Darkspawn warrior or lord due to it being a non-hostile creature, and was released back to it's homeworld until he was found by Emperor Fang who tamed the creature to serve as his pet and spy. But later, some time after Emperor Fang's usurp by Dark Dragon, Nivawk reformed and became a spy for the good guys, including the Scourge Rebellion.