A Brotherhood of Makuta Fortress
In Bionicle, there were several different factions with the most power or in greatest population. Each employed agents to do their duties. They are listed here, with basic descriptions.
Dark Hunters
The Dark Hunters were a group of beings headed by The Shadowed One, specializing in bounty hunting, assassination, and espionage. They included creatures of various species, and would do anything if the price is right. They were neutral in quarrels that aren't their own, but have fought for and against both sides. Some were extremely intelligent, others dim-witted but powerful.
Brotherhood of Makuta
The antagonists of the Bionicle. The Brotherhood of Makuta was an organization of the shapeshifting Makuta species who were once loyal to Mata Nui. It was their job to create and modify species as they saw fit to ensure the universe would remain healthy and free of decay. After crushing the League of Six Kingdoms, they began to have thoughts of taking over. Only when Makuta Mutran met with the entity Tren Krom did they began to enact these plans. Makuta Teridax somehow knocked Mata Nui unconscious and slowly dying. This is part of a larger scheme which, somehow, actually relies on the Toa Nuva completing their destinies. They are cruel, ruthless and intelligent, and will stop at nothing to become rulers of the Bionicle Universe.
Visorak
The Visorak were a spider-like race composed of several swarms (analogous to the Bohrok, seen below) under a military dictatorship ruled by Sidorak and his lieutenant, Roodaka. Wielding Rhotuka, machine weaponry, Rahi slaves, and a strange mutating poison, they took over Metru Nui under the banner of a vengeful Makuta.
Order of Mata Nui
The Order of Mata Nui was a very secretive organization, only known by few. Most were fiercely loyal to Mata Nui. They were associated with beings of great power and unknown race, and fight the Brotherhood of Makuta. If Axonn, Brutaka, Hydraxon and Botar are to set any precedent, the Order of Mata Nui had members, powers and weapons of every type.
League of the Six Kingdoms/Barraki
The League of the Six Kingdoms was made up of six ruthless warlords, called the Barraki, and their armies. They ruled and conquered all that they could reach. The Barraki then decided that they wanted to rebel against Mata Nui himself.As they were prepairing for battle, though, the Brotherhood of Makuta came and crushed the armies. The Barraki, were then banished to The Pit for plotting against Mata Nui. Because of the mutagen in the sunken-underwater Mahri Nui, the Barraki have mutated and taken the appearance of water Rahi. They used Squids and their fierce reputation to keep the ocean in check and menace the Matoran, while at the same time, searching for the salvation of the Mask of Life. Recently, the Order of Mata Nui allowed them to reform their organization, this time, to focus their attacks on the Brotherhood of Makuta.
Hand of Artakha
The Hand of Artakha was a mysterious ancient organization that did not exist for most of the BIONICLE. However, it was very influential. Like the Order of Mata Nui and the Dark Hunters, its members were all powerful, and of ambiguous various species. They were the predecessor to the Toa, being public defenders of justice, and disbanded shortly after the Toa were created. Many members went on to become members of the Order of Mata Nui, including Axonn and Hydraxon, while others later joined the Dark Hunters, such as "Shadow Stealer".