The Bohrok Swarm - once intended to simply scour the island of Mata Nui and nothing more - has deemed the Great War a threat to the health of the Great Spirit, turning the full attention of the Swarm upon the rest of the universe. With the unwavering determination of a single hivemind, they will attempt to impose their vision of order by any means necessary.
Bohrok come in six breeds, each of which corresponds to an element. The Bohrok themselves are actually robotic suits, operated by small organic creatures called Krana; under the right circumstances, Krana can also control other beings, taking the place of a Kanohi mask and adding their victim to the Bohrok hivemind. In the event of damage to the Bohrok shell - or to attempt to take over the mind of another being - the Krana can eject itself, ensuring that even a downed Bohrok is dangerous to approach. Krana come in eight varieties, each of which serves a different function within the Swarm. They are supplemented by the Bohrok Va, small servitor automata that can re-stock Krana as needed.
The Bohrok are led by their twin Bahrag queens, Cahdok and Gahdok, and their will is carried out by the six elite Bohrok-Kal. The Bahrag are a dual threat, capable of moving independently of each other and wielding significantly-enhanced versions of the elemental powers used by the six Bohrok breeds. The Bohrok-Kal have their own unique elemental abilities, each unlike anything else found in the Swarm, and are a force to be reckoned with.