Kralhi
The Prototype Enforcers Metru Nui Tried to Forget
The first attempt at automated law enforcement in Metru Nui, the Kralhi were ordered destroyed for draining their captives into uselessness, and some later served the exiled Archivist Mavrah beyond the silver sea.
The Kralhi were the first robotic law enforcers built for Metru NuiMetru NuiThe city beneath Mata Nui functions as the Great Spirit's brain, housing the Matoran whose labor keeps the god alive., made to the design of the Onu-MatoranOnu-MatoranEarth-wielding Matoran of the deep who adapted to darkness and built the Matoran Universe's defensive cavalry. NuparuNuparuAn Onu-Matoran engineer from Metru Nui who built the Boxor and rose to become a Toa of Earth despite no warrior destiny., based on an idea from Ko-MetruKo-MetruKo-Metru was Metru Nui's frozen intellectual quarter, home to the scholarly Ko-Matoran race., to enforce the rules of TuragaTuragaFormer Toa who fulfilled their destiny and transformed into leaders. Turaga wield Noble Kanohi masks and weakened elemental powers, guiding their communities. DumeDumeDume is a Turaga of Fire and the former ruler of Metru Nui, distinguished by his red and black coloring and the Noble Kanohi Kiril, the Mask of Regeneration. As a member of the Turaga of Metru Nui, he wields a Staff of Office and commands a weakened mastery of Fire. He later resides on the reformed Spherus Magna.. They were clockwork machines that subdued lawbreakers with an energy bubble fired from the tail. They worked in a narrow technical sense and failed in every practical one, because their captives were too weak to work for days afterwards. Dume ordered them destroyed, and the survivors scattered, some into hiding in the city and some out across the silver sea, where seven of them ended up serving the exiled ArchivistArchivistA Matoran keeper of records and relics, the Archivist held one of Metru Nui's deadliest jobs. MavrahMavrahA Metru Nui Archivist who fled his city rather than let Turaga Dume cull his pet sea Rahi, drowned in a feeding frenzy a thousand years before the Great Cataclysm, and was rediscovered alive aboard the Red Star.. (BIONICLE Adventures 5: Voyage of Fear; BIONICLE: Metru Nui, City of Legends; BIONICLE: Encyclopedia Updated)
Commission and design#
The Kralhi were built long before the VahkiVahkiMetru Nui's mechanical law enforcement squads, designed to maintain rigid order but ultimately undermined by chaos beyond their programming., out of a perceived need for law enforcers in Metru NuiMetru NuiThe city beneath Mata Nui functions as the Great Spirit's brain, housing the Matoran whose labor keeps the god alive.. The idea came from Ko-MetruKo-MetruKo-Metru was Metru Nui's frozen intellectual quarter, home to the scholarly Ko-Matoran race., NuparuNuparuAn Onu-Matoran engineer from Metru Nui who built the Boxor and rose to become a Toa of Earth despite no warrior destiny., an Onu-MatoranOnu-MatoranEarth-wielding Matoran of the deep who adapted to darkness and built the Matoran Universe's defensive cavalry., produced the design, and the finished machines began enforcing the rules laid down by TuragaTuragaFormer Toa who fulfilled their destiny and transformed into leaders. Turaga wield Noble Kanohi masks and weakened elemental powers, guiding their communities. DumeDumeDume is a Turaga of Fire and the former ruler of Metru Nui, distinguished by his red and black coloring and the Noble Kanohi Kiril, the Mask of Regeneration. As a member of the Turaga of Metru Nui, he wields a Staff of Office and commands a weakened mastery of Fire. He later resides on the reformed Spherus Magna.. (BIONICLE Adventures 5: Voyage of Fear; BIONICLE: Metru Nui, City of Legends; BIONICLE: Encyclopedia Updated)
Like the Vahki after them, the Kralhi ran on complex clockwork machinery. About two dozen were built. They also carried built-in sound recorders that could play back what they had heard. (BIONICLE Adventures 5: Voyage of Fear; BIONICLE 17: Disks of Danger)
The core of the design was the energy bubble. Launched from the tail, it surrounded a disruptive being and drained their energy, so that they could no longer cause trouble. (BIONICLE Adventures 5: Voyage of Fear)
The energy-drain problem#
The Kralhi did what they were built to do. The bubble stopped any MatoranMatoranThe most abundant species in the Matoran Universe, chosen by Mata Nui to inhabit and maintain his cosmic body. caught in it, and the captive caused no more trouble. As a way of halting an offence, it worked. (BIONICLE Adventures 5: Voyage of Fear)
As a way of keeping the city running, it did not. A MatoranMatoranThe most abundant species in the Matoran Universe, chosen by Mata Nui to inhabit and maintain his cosmic body. brought in by a Kralhi was too weak to go back to work for several days. In a city built around constant work, every arrest took a worker off the job, and the robots were judged ineffective. Nuju later dismissed them as clanking energy vampires, and the failed project became known as "Nuparu's folly". (BIONICLE Adventures 5: Voyage of Fear)
The project had solved the wrong half of the problem, and Dume ordered the robots destroyed. (BIONICLE Adventures 5: Voyage of Fear)
Decommissioning and resistance#
The Kralhi refused to be taken apart. Their drive for self-preservation led them to resist Dume's order. A few were shut down and scrapped by the MatoranMatoranThe most abundant species in the Matoran Universe, chosen by Mata Nui to inhabit and maintain his cosmic body., but most fought back hard and stayed active. (BIONICLE Adventures 5: Voyage of Fear; BIONICLE 17: Disks of Danger; BIONICLE: Metru Nui, City of Legends)
Once the VahkiVahkiMetru Nui's mechanical law enforcement squads, designed to maintain rigid order but ultimately undermined by chaos beyond their programming. had been built, they helped the Matoran drive the Kralhi away. Seven of them left Metru NuiMetru NuiThe city beneath Mata Nui functions as the Great Spirit's brain, housing the Matoran whose labor keeps the god alive. entirely, fleeing across the silver sea to the Great BarrierThe Great BarrierThe enormous underground dome of rock and solid Protodermis that enclosed Metru Nui and the Silver Sea, sealed Teridax into a cliff face, and was finally cracked open during the Great Cataclysm.. (BIONICLE Adventures 5: Voyage of Fear)
Others stayed behind. A few took refuge in little-used parts of the ArchivesThe Archives of Metru NuiThe Archives of Onu-Metru were the central repository of Matoran knowledge and Rahi specimens, maintained by the Archivist Corps beneath the city's surface., and others in Ko-MetruKo-MetruKo-Metru was Metru Nui's frozen intellectual quarter, home to the scholarly Ko-Matoran race.. The books never say what became of them. (BIONICLE: Metru Nui, City of Legends; BIONICLE: Encyclopedia Updated)
Mavrah's command#
The seven that fled found a new master in MavrahMavrahA Metru Nui Archivist who fled his city rather than let Turaga Dume cull his pet sea Rahi, drowned in a feeding frenzy a thousand years before the Great Cataclysm, and was rediscovered alive aboard the Red Star., an Onu-MatoranOnu-MatoranEarth-wielding Matoran of the deep who adapted to darkness and built the Matoran Universe's defensive cavalry. ArchivistArchivistA Matoran keeper of records and relics, the Archivist held one of Metru Nui's deadliest jobs. who had left Metru NuiMetru NuiThe city beneath Mata Nui functions as the Great Spirit's brain, housing the Matoran whose labor keeps the god alive. with a group of ancient sea RahiRahiThe Rahi were the biomechanical wildlife of the Matoran Universe, built largely by the Brotherhood of Makuta, ranging from background fauna to engineered war beasts. rather than give them up. The Kralhi formed an alliance with him and served as his guards and servants. (BIONICLE Adventures 5: Voyage of Fear)
Mavrah also modified some of them to fire KanokaKanoka DisksMetru Nui's most versatile artifact: flying disks equally at home in sport, combat, and crafting. disks. With no city to keep working, the energy bubble that had ended their official career was no longer a drawback. (BIONICLE Adventures 5: Voyage of Fear)
Some of Mavrah's Kralhi were eager to kill. (BIONICLE Adventures 5: Voyage of Fear)
The waterway battle#
The arrangement broke when the Toa MetruToa Metru and Toa HordikaSix Matoran elevated by Lhikan to save their city, mutated by Visorak venom, and restored in time to deliver the population to safety. passed through on their way to Mata NuiMata Nui (Location)An island created by accident on the Great Spirit's face, home to the Matoran for a thousand years. with the sleeping MatoranMatoranThe most abundant species in the Matoran Universe, chosen by Mata Nui to inhabit and maintain his cosmic body. after the Great CataclysmThe Great CataclysmThe day Makuta Teridax put the Great Spirit to sleep, the Great Spirit Robot fell from the sky, Metru Nui flooded, and Voya Nui tore loose from the Southern Continent.. Six Kralhi spotted them, and one recorded VakamaVakamaA Ta-Metru maskmaker transformed into the Toa Metru of Fire, leader of his team through the Visorak war, and Turaga of Ta-Koro for a thousand years.'s words and played them back for MavrahMavrahA Metru Nui Archivist who fled his city rather than let Turaga Dume cull his pet sea Rahi, drowned in a feeding frenzy a thousand years before the Great Cataclysm, and was rediscovered alive aboard the Red Star.. (BIONICLE Adventures 5: Voyage of Fear)
Mavrah knew nothing of what had happened in Metru NuiMetru NuiThe city beneath Mata Nui functions as the Great Spirit's brain, housing the Matoran whose labor keeps the god alive. and was convinced the Toa had come to take him back. He ordered the Kralhi to capture them. The robots trapped each Toa in an energy bubble and carried them back to his lair. (BIONICLE Adventures 5: Voyage of Fear)
Three Kralhi stood guard as the Toa woke. When OnewaOnewaOnewa served as Toa Metru of Stone, led Po-Koro through the Dark Time, and constructed the Metru Nui statue honoring the fallen Toa Mahri Matoro. tried to use his KomauKanohi KomauThe Mask of Mind Control, forged from Freeze, Weaken, and Remove Poison Kanoka in Metru Nui, which lets its wearer take over the mind of a weaker-willed being. on Mavrah, the robots fired a weakness disk at him. VakamaVakamaA Ta-Metru maskmaker transformed into the Toa Metru of Fire, leader of his team through the Visorak war, and Turaga of Ta-Koro for a thousand years. slipped away using his HunaHunaThe Kanohi Huna granted full invisibility to its wearer, with the limitation that the user's shadow remained visible and detectable., and when Mavrah sent two Kralhi after him, he destroyed one with fire and the other with a freeze disk. Onewa crushed another into a cube with the stone floor, and NujuNujuNuju served as a Ko-Metru seer, Toa Metru of Ice, and Turaga of Ko-Koro who spoke only in bird calls translated by Matoro. sealed one's tail with ice just as it was about to fire, making it explode. Once reunited, the Toa destroyed most of the rest, and the last was destroyed by one of Mavrah's ancient Rahi before the Toa escaped. (BIONICLE Adventures 5: Voyage of Fear)
Legacy in the Archives#
The Kralhi that stayed in Metru NuiMetru NuiThe city beneath Mata Nui functions as the Great Spirit's brain, housing the Matoran whose labor keeps the god alive. remained an open question. Reference books describe them hiding in the less used sections of the ArchivesThe Archives of Metru NuiThe Archives of Onu-Metru were the central repository of Matoran knowledge and Rahi specimens, maintained by the Archivist Corps beneath the city's surface. and in Ko-MetruKo-MetruKo-Metru was Metru Nui's frozen intellectual quarter, home to the scholarly Ko-Matoran race., and nothing in the stories says they were ever found. (BIONICLE: Metru Nui, City of Legends; BIONICLE: Encyclopedia Updated)
Their longer significance lay in what they showed about policing the city. The Kralhi proved that robotic enforcers could work, and also that stopping a lawbreaker was not the same as keeping a city working. Their successors, the VahkiVahkiMetru Nui's mechanical law enforcement squads, designed to maintain rigid order but ultimately undermined by chaos beyond their programming., used stun staffs that left their targets able to return to work. (BIONICLE Adventures 5: Voyage of Fear; BIONICLE: Encyclopedia Updated)
Even after being formally retired, the Kralhi that reached Mavrah went on serving a MatoranMatoranThe most abundant species in the Matoran Universe, chosen by Mata Nui to inhabit and maintain his cosmic body. master, out of reach of the city that had built them. Whether any of the ones hidden in Metru Nui ever acted again is never revealed. (BIONICLE Adventures 5: Voyage of Fear; BIONICLE: Encyclopedia Updated)
Frequently asked questions
- What were the Kralhi in Bionicle?
- The Kralhi were the first robotic law enforcers built for Metru Nui, made to the Onu-Matoran Nuparu's design. They were clockwork machines that fired energy bubbles from their tails, and about two dozen were built.
- Why were the Kralhi decommissioned?
- The Kralhi's energy bubble drained a captive's energy, leaving Matoran too weak to work for several days. In a city built around constant work, that made the robots ineffective, so Turaga Dume ordered them destroyed.
- What replaced the Kralhi?
- The Kralhi were replaced by the Vahki, also built by Nuparu. The Vahki carried stun staffs that affected a target's mind rather than draining their energy, so captives could go back to work.
- What happened when the Matoran tried to scrap the Kralhi?
- The Kralhi refused to be taken apart. A few were scrapped, but most fought back, and once the Vahki were built they helped the Matoran drive the Kralhi away. Seven fled across the silver sea to the Great Barrier, while others hid in the Archives and Ko-Metru.
- How did Mavrah end up commanding the Kralhi?
- The exiled Archivist Mavrah had left Metru Nui with a group of ancient sea Rahi. The seven Kralhi that fled the city allied with him and became his guards and servants, until the Toa Metru passed through and destroyed them in battle.
Sources
- BookBIONICLE Adventures 5: Voyage of Fear, Greg Farshtey, Scholastic, 2004
- BookBIONICLE: Metru Nui, City of Legends, Greg Farshtey, Scholastic, 2004
- BookBIONICLE: Encyclopedia Updated, Greg Farshtey, Scholastic, 2007
- ComicBIONICLE 17: Disks of Danger, Greg Farshtey, LEGO / DC Comics, 2004
Spotted a factual error or a primary source we missed? Email a correction. Every flagged claim gets reviewed.
Followed from this entry

The Archives of Metru Nui
The Archives of Onu-Metru were the central repository of Matoran knowledge and Rahi specimens, maintained by the Archivist Corps beneath the city's surface.

Vahki
Metru Nui's mechanical law enforcement squads, designed to maintain rigid order but ultimately undermined by chaos beyond their programming.

The Great Barrier
The enormous underground dome of rock and solid Protodermis that enclosed Metru Nui and the Silver Sea, sealed Teridax into a cliff face, and was finally cracked open during the Great Cataclysm.
Mavrah
A Metru Nui Archivist who fled his city rather than let Turaga Dume cull his pet sea Rahi, drowned in a feeding frenzy a thousand years before the Great Cataclysm, and was rediscovered alive aboard the Red Star.

The Great Cataclysm
The day Makuta Teridax put the Great Spirit to sleep, the Great Spirit Robot fell from the sky, Metru Nui flooded, and Voya Nui tore loose from the Southern Continent.

Vakama
A Ta-Metru maskmaker transformed into the Toa Metru of Fire, leader of his team through the Visorak war, and Turaga of Ta-Koro for a thousand years.
Mentioned in13 entries
BIONICLE Adventures: the ten-book series that told the Toa Metru story
BIONICLE Adventures is the second BIONICLE book series, ten titles written by Greg Farshtey between 2004 and 2005, covering the Toa Metru a thousand years earlier during and after the Great Cataclysm.
Bordakh
The Vahki model assigned to Ga-Metru, the Bordakh patrolled the canals and schools of the academic district and carried Staffs of Loyalty that turned any Matoran they struck into a willing informant against their own friends.
Chief Archivist
The unnamed Onu-Matoran who ran the Archives of Metru Nui, held the keys to its deepest sub-levels and answered to Turaga Dume.
Engineer
Engineers, also called Inventors, were Matoran whose work was to build the machinery and devices that improved life across the Matoran Universe, a trade most famously held by Nuparu, builder of the Vahki and the Boxor.
Keerakh
The Vahki model assigned to Ko-Metru, the Keerakh enforced silence in the Knowledge Towers and subdued lawbreakers with staffs that scrambled a Matoran's sense of time and place.
Kraahu
The specialist Vahki combiner formed from Zadakh, Keerakh, and Bordakh components, the Kraahu carried knowledge centres throughout its body, could split apart to fight six directions at once, and as a single unit could spray a cloud of stun gas.
Matoran Spheres
The silver hibernation pods used by Teridax, posing as Turaga Dume, to capture, store, and transport the entire Matoran population of Metru Nui during the Great Cataclysm.
Mavrah
A Metru Nui Archivist who fled his city rather than let Turaga Dume cull his pet sea Rahi, drowned in a feeding frenzy a thousand years before the Great Cataclysm, and was rediscovered alive aboard the Red Star.
Sea Rahi
A class of massive ancient sea Rahi recovered by the Onu-Metru Archives, shut down by Turaga Dume for being too dangerous, and led into the silver sea by the Onu-Matoran Mavrah to an abandoned outpost beyond the Great Barrier.
The Lhikan: Vahki Transport of the Toa Metru
The first of the two Vahki Transports the Toa Metru christened in honor of the fallen Toa Lhikan, the vessel that carried six Matoran in spheres across the Silver Sea to Mata Nui after the Great Cataclysm.
Underwater Rahi Study
An Onu-Metru Archives project to study a group of ancient sea Rahi recovered off the coast, ended on Turaga Dume's cull order, and revived as a fugitive expedition in the subterranean waterways beneath Metru Nui.
Voyage of Fear
The Toa Metru's first voyage from a broken Metru Nui to the island of Mata Nui aboard the Vahki Transport Lhikan, the ambush by surviving Nuurakh, and the standoff with the exiled Archivist Mavrah and his prehistoric sea Rahi.
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