Bankizoku Gaiark
(Savage Machine Family/Clan Gaiark)

The Gaiark come from the Machine World and their main aim is to pollute the Earth to make it suitable for them, they do not want to destroy it. There are three main ministers. The Gaiark based themselves in a fortress called the Hellgaille Palace on an isolated island. Despire being evil, the three are rather kind to each other and geninuely care for each other.

Ground Assault Minister Yogostein
Height: 218 cm to 56.7 m
Weight: 69 kg to 295 kg to 767 tons
Yogostein is in charge of polluting the Earth, he is the leader of the three. He is armed with a spear. He might look gruff and tough, but in actuality, he as flappable and as susceptible to overestimating his success as the other ministers. He is not above using his subordinates to his advantage. He ends his sentences with "Nari." He revels in the success of his subordinate Hiramechimedes and admires and beleives in him very much. Despite continuous failure, his faith and esteem he felt for his vice-minister never faded as he showed concern for Hiramechimedes' well-being and has been in a state of mourning since his death before leaving Hellgaille
Palace to clear his head and find himself. By the time he returned, Yogostein was more rage-filled and decided to rely on his own power, creating Hammer Banki to destroy the world rather than remake it into an ideal environment for the Gaiark. It was after his creation was destroyed that Yogostein saw the error of his ways and the other Ministers forgave him for his reckless action. However, Yogostein resumed acting on his own when he begins a new project to unearth the Horonderthal from his rest, successfully rusting Sosuke. After Horonderthal was destroyed, he upgraded himself as the new Horonderthal King to rust the entire city. In Episode 36, he took the Change Souls within himself and the Go-onger tried fighting him with their powers. They managed to climb into him to retrieve their Change Souls. He was defeated by the newly formed Engine-Oh G12. He was revived and finally destroyed by Sosuke in a one-on-one duel.

Aerial Assault Minister Kitaneidas
Height: 215 m
Weight: 266 kg
Kitaneidas enjoys polluting the skies and atmosphere. He wields a staff. He ends his sentences with "Zoyo." He experimented with Bikkurium's potent abilities prior to using it on Barbaric Machine Beasts. He and Kegalesia didn't quite understand Yogostein's abandonment, but when he was destroyed by the Go-Onger, Kitaneidas swore revenge. Kitaneidas is reduced to a mere henchman when Yogoshimacritein arrives and is forced to obey him. He is agitated when Yogoshimacritein uses him as a shield against the Go-ongers, and as a final act, he destroys the Inifinite Wastebin before he is forced to shutdown by Yogoshimacritein.

Aquatic Assault Minister Kegalesia
Height: 191 cm to 49.6 m
Weight: 54 kg to 140.5 tons
When Kegaleshia steams up, her comrades can turn it off by turning her valve on her helmet. In Episode 4, she is the first to face the Go-Ongers and it is discovered she is machinery underneath, meaning she is an android. She can also quickly heal. She ends her sentences with "Ojaru", is a heavy drinker, and hates to be called "Old Lady." In Episode 14, she donned the guise of Rena Kegareshi to figure out the secret of a dojo owner who bested one of her minions and Hanto falls in love with her and calls her beautiful and pure, which is offensive to her, so she develops a vendetta towards him. She has helped Go-On Silver and Go-on Yellow as part of the singing group G3 to defeat a common enemy. But when insulted by a little girl, she grew huge in rage. She is annoyed when Yogoshimacritein uses her and Kitaneidas
as shields against the Go-onger's attacks. As a final act, she assists destroy the Infinite Wastebin before being heavily damaged by Yogoshimacritein. She gives the location of the other Go-ongers and Deus Haguru Magear to Go-on Red, Blue, and Yellow before shutting down. Much like some of her counterparts before her, a person resembling her was seen at the end of the finale. In the Movie, Kegalesia accidentally separates her Kegalesia Soul from her body and set her soul in Bomper by the other Ministers to convert the robot into Bompelesia so they could set a trap. However, Bomper regained control and ejected the Kegalesia Soul prior to being reinstalled back in her body.

Barbaric Machine Soldiers Ugatz
Gaiarc's android grunts fight the Go-Onger and pilot the Gaiarc mecha. When Nigorl arrives, he brings his own feminine Beauty Ugatz in Episode 26, which are stronger than the regular Ugatz.

Barbaric Dohma
The Gaiarc's mecha that the Ugatz and the ministers pilot. They are capable of leaping in the air like frogs or to actually fly in the air.

Barbaric Dohma SP
The personal jet fighter of Hiramechimedes is a Dohma that looks more like a Mantis. Each able to hold up to four Barbaric Dohma on itself to resemble a classic WW1 airplane.

Land Pollution Vice-Minister Hiramechimedes
He is Yogostein's partner and is the best tactical intelligence of Gaiarc. In the Machine World, he planned to kill Yogostein and take his place, feeling unnoticed, when he took the shock of his life and was promoted to Vice-Minister by Yogostein. Whenever inspired with a plan, the three lights on his head flash. In spite of his lower ranking, Hiramechimedes is feared by the Engines, his victories against them made frightened husks of their former selves. However, on the day the Gaiarc were expelled from Machine World, Hiramechimedes
mysteriously disappeared during the fight only to resurface months later in the Human World. According to him, when the trio left, the Wing Engines suddenly appeared and sent him running to the Human World. He has a special class of screws that can strengthen the Ugatz. His special attacks are the Equilateral Triangle Slash and Isosceles Right Triangle Slash. A running gag with Hiramechimedes is that the Go-ongers, besides Renn, mispronounce his name. After too many failures, Yogostein and Hiramechimedes orchestrate a banishment to fool their enemies, including the other two ministers. Hira fools the five Go-Onger that he is wounded and to convince Go-On Gold to race him to the palace, but in reality it was a regular island. Using their strength together, the 7 heroes defeated him. In Episode 23, he decided brains wasn't enough and wanted to use pure force. In order to restore the honor of the Earth branch and Yogo he felt he shamed, he uses enough Bikkurium to power 100 Bankijyu to undergo a upgrade into the powerful Detaramedes, making him unstable and mad. He was finally destroyed by the random and unplanned fighting styles of Sosuke. His last words were to Yogostein. In episode 24, the Go-ongers visit a shrine in the woods and encounter the ghost of Hiramechimedes, refering to himself as Urameshimedes and has teamed up with a being called Bakki, from Samurai World. Hiramechimedes merged with Bakki, making him big and is finally put to rest by a special G9 Grand Prix.

Water Pollution Prince Nigorl zo Arelunbra
Height: 209cm to 52.5 m
Weight: 222kg to 610.5 tons
Arelunbra is the prince of the Arelunbra Family, that are sea-based androids who terrorized the Machine World with their Water Pollution Machine Knights before the Gaiarc appeared. Though the Arelunbra were wiped out, only Nigorl survived and ended up in the Human World in a state of supended animation until the Gaiarc uncovered and reactivated him. Nigorl becomes Kegalesia's protege, refering to her as "princess." Nigorl has an unusual liking to things he considers beautiful and seeks the affections of another. He formerly appears in Episode 26 and is destroyed in the same episode.

Height: 57.6 m
Weight: 645 tons
He is of a legendary clan of giant Clockwork Savage Machines whom exterminated dinosaurs on the earth 65 million years ago with his violence-inducing Horonden Wave. He battled with the Ancient Engines at that time, with their fight ending up with both sides fossilized within a mountain. Yogostein made it his goal to uncover him and had Drill Banki do it but they accidentally free the Ancient Engines instead. But after personally finding the extact location of Horonderthal, Yogostein awakens him in Episode 34. In Episode 35, he upgrades him so that his attack can affect Kyoretsu-Oh and Kyoretsu-Oh is turned against the Go-onger. However, in spite of his modern-time upgrades, the Horonderthal became the first to be destroyed by Engine-Oh G12 with Yogostein taking the Horonderthal's power for himself. His name is from the Japanese word for "extinct" (Horonderu) and "Neanderthal."

He is the cleaning minister, who "cleans" the slate of Braneworlds he has visited, destroying the Sound World, the Magic World, and the Prism World to acquire a special energy called Dokkirium. Arriving in the Human World in Episode 42, Kireizky intervened during Engine-Oh G9's fight with Bin Banki before formally introducing himself. Kireizky is armed with Seven Cleaning Tools such as Duster Blade. His other weapons are Broom Shotgun and the Anti-Soul Floorcloth that can absorb Engine-Soul based attacks and sends them back or be wrung into the Floorcloth Grenade, the Dustpan Shield, and Cotton Swab Kunai. The Infinite Wastebin allows him to manipulate dimensional space and can suck people in. But once losing the wastebin, Kireizky swallows the Dokkirium to undergo Super Industrial Revolution and used his Bucket Bazooka. Engine-Oh G12 destroyed him in Episode 44.

He is the Prime Minister of the Gaiark and Yogostein's father, he is responsible for forcing the Gian Race Engines into the verge of extinction. Overseeing the destruction of the three Braneworlds by Kireizky, Yogoshimacritein uses his fallen minion's Infinite Wastebin to enter the Human World in Episode 46. He used the wastebin as a means to feed from in order for him to use his signature attack Justice Dissolution, which can vaporize those hits. He uses it to take out all the heroes except for the main three Go-onger and their partner Engines. Yogoshimacritein is the most ruthless of the Gaiark, easily using both Kegalesia and Kitaneidas as shields if need be. After losing the Infinite Wastebin to the ministers, Yogoshimacritein fatally damages them both before making his way to the Deus Haguruma Magear to power himself up. His attacks are Puppet Regime which can turn his subordinates into his puppets, and Ration Provision Bullet. He didn't think so highly of his son. Much like Yogostein, he ends his sentences with "Narina".

He is Yogoshimacritein's right-hand man and appears in Episode 47. He destroyed the three Braneworlds with Kireizky. He is a user of kenpo named Heaven and Earth Litter Constitution and his trademark attack is the Heaven and Earth Reversal, ingesting the energy attack of a opponent and reflecting back. His other attack, Heaven and Earth Futility, produces a shockwave that levels buildings to the ground. Once the Go-ongers found a means to counter his signature move, Chirakasonne ingests Dokkirium and defeats both Engine-Oh and Seiku-Oh easily. But GunBir-Oh overloads Chirakasonne with its attack.