Nynrah Ghosts

The Nynrah Ghosts were a group of approximately four dozen Matoran of Iron crafters from the island of Nynrah. Little is known about them, except that they modified the armors of the Brotherhood of Makuta when the Makuta evolved. They also created the Nynrah Ghostblasters.

Other devices they created included the Exo-Toa, Zamor Launchers, and "Fohrok." However, they secretly sabotaged the Fohrok. Upon learning of this, the Brotherhood of Makuta hired multiple Dark Hunters to execute the Matoran responsible. Eventually, only two Nynrah Ghosts were left. One of them became a Dark Hunter named Phantom while the other left to Stelt as a rogue Ghost. He modified Vultraz's Skyfighter and, due to his slow response to Mazeka, has a crushed mask.

At some point, they took the Matoran Gaardus and transformed him into a creature meant to defend Nynrah. He later killed Nynrah Ghost exiles.

Dark Mirror
In the "Toa Empire" Parallel Universe, the Ghosts were wiped out by a team of Toa led by Nidhiki solely because the Nynrah Ghosts were capable of making something that could be a threat to the Toa Empire.

The Kingdom
They evacuated to Mata Nui after the Great Spirit's death and still play at secrecy. One Ghost gave Takanuva his Power Lance and Midak Skyblaster. Another Nynrah Ghost became part of Turaga Takanuva's ruling council.