Vahki

Vahki were law enforcement robots created by Nuparu to protect Matoran and stop criminals on Metru Nui. Nuparu created nine types of Vahki, one of them a prototype and two elite. They are:
 * Zadakh
 * Bordakh
 * Rorzakh
 * Nuurakh
 * Vorzakh
 * Keerakh
 * Kranua
 * Kraahu
 * Kralhi

Most Vahki could launch Kanoka Disks from their mouths to attack enemies. Many of them also carried staffs with them, which they could disable criminals with. They could walk on two or four legs, depending on the speed needed to persue the enemy. The Vahki recieved their power from the Coliseum, and reported to a center in each Metru, though during the time leading up to the Great Cataclysm they reported directly to Dume.

Vahki were essential in the Makuta's plan to become the diety of the Matoran. Under the guise of Turaga Dume, Makuta ordered the Vahki to capture all the Matoran in each sector of Metru Nui. When this took to slowly, he ordered all Matoran to the Coliseum and into pods. After Makuta sucked all the energy from the city up, the power core in the Coliseum shut down, as did the command centers. No longer driven by any urge to stop crime, the Vahki in the city dropped what they were doing, fell to the ground, and turned off. They were presumably tied up by the Visorak.