The Seven Barian Emperors are a group composed of elite Barians within the Yu-Gi-Oh! ZEXAL anime which are led by Nasch. They have an agenda of stealing the "Numbers" and destroying the Astral World taking part in the Interdimensional War, and they serve as the main antagonist faction. According to Vector, there were originally seven of them, but after Nash and Marin's disappearance they were left with five and Dumon inheriting control.
Members of the Seven Barian Emperors are loosely named after one of the stars of the Big Dipper: Dumon after Dubhe, Alito after Alioth, Mizar after Mizar, Girag after Merak, Vector after Phecda (and also a nod to Hector of Greek Mythology), Nasch after Benetnasch and Merag after Megrez.
While on Earth, Barian Emperors are forced to take on a human form, not knowing that this form was the one they had from the time they were humans, although Dumon apparently only needs to do this if his Baria Lapis is damaged. The only major resemblance between both their Barian and human form is their hair, which only changes color. As energy beings, they are tolerant to pain, even in human form; Girag was able to take a punch in the face from Fender without so much as a flinch. After Earth and the Barian World began to merge, the Emperors were able to maintain their Barian forms on Earth.
They can travel from the Barian World using Overlay Networks and can also utilize the ability on Earth, vanishing and reappearing on a whim. Mizar showed the ability to fire energy balls for offensive purposes, though they do not cause lasting damage. These abilities can also be granted to humans. Vetrix, who made a contract with the Barians, was able to produce energy balls and use the aforementioned networks to travel.
The Seven Emperors also possess the ability to Rank-Up their Xyz Monsters by the use of "Rank-Up-Magic Barian's Force", which lets them Summon "Number C" and "CXyz" monsters. "CXyz" monsters originate from the Barian World and are produced there as "weapons" to defeat the "Numbers". While in human form, Barians cannot wield them, but they can use "Rank-Up-Magic Barian's Force" to brainwash humans into doing so for them. The brainwashing effect appears to vary from the individual controller; Girag's victims retain their personality but become obsessed with the Barian World, while Vector's victims are similar to sleeper agents, retaining their original personalities until the brainwashing activates at a later time, and when Alito controlled Nistro the latter was completely robbed of free will, period. In addition, if a Barian were to lose a Duel to a person using a "CXyz", they would vanish from existence, just as Astral would if he lost to a "Number".
Barian's Chaos DrawThe Barian's Chaos Draw (バリアンズ・カオス・ドロー Barianzu Kaosu Dorō) is an ability used by Nash. It is currently unknown what this ability does, although it is insinuated to be similar to Shining Draw. However, it should be noted that when Nash used this ability, it resonated with all the other Emperors in their Duels and all of them obtained the ability. When this power is used, the user is surrounded by a reddish-purple column of light. Upon using it, all Seven Barian Emperors(with the exception of Vector) drew Rank-Up-Magic The Seventh One.
Each of them bears a connection to a Number ruins and the Legendary Number that is hidden there. As confirmed by Astral and Dumon, the Barian Emperors were human once, with their previous life being described in the legend in each ruin.
Yu-Gi-Oh! ZEXAL II
The Barians are at war with Astral World and seek to protect it from its envoy, Astral. One Barian, Mizar, specified that if they do not, then their own world will have "no future". For that reason, the Barians are bent on acquiring the "Numbers" to find the location of "Numeron Code" - the "God Card" that created the world and can decide fate. They cannot gather the "Numbers" themselves, so the Seven Barian Emperors manipulated and exploited humans (including Dr. Faker and Vetrix) into doing so for them.
With the defeat of both human pawns, Vector and Dumon decided that they would have to intervene directly. To that end, he sent Girag to Earth. On Earth, Barians can assume human form, though they do not decide their appearance and are unable to wield "CXyz" monsters. Following Girag's failed attempts to get Yuma's "Numbers", back in the Barian World Dumon sends Alito to try to take the "Numbers" from Yuma.
After the constant failures of Girag and Alito, Dumon decides to send Mizar to Earth, giving him three "Baria Sphere Cubes" which let Barians collect "Numbers" themselves. Mizar's arrival was by a giant energy ball crashing into a forest, causing a deep crater. Mizar's attempt to defeat Yuma was interrupted by Kite Tenjo, who took over the Duel. Mizar ended up cancelling the Duel when the power of his "Number C107: Neo Galaxy-Eyes Tachyon Dragon" nearly destroyed the Barian Sphere Field.
Girag would then make another attempt, brainwashing a whole army of students, but Yuma was saved by Alito, who wished to defeat Yuma himself. Alito deployed his Barian's Sphere Cube, but was ultimately defeated by the power of ZEXAL. He was later ambushed, prompting Girag to take revenge, believing Vector had been the one to ambush him. Girag ended up Dueling "Ray" and Yuma at the same time in his own Sphere Field. "Ray" revealed his identity as a Barian's Guardian and gave Yuma "Rank-Up-Magic Limited Barian's Force", allowing him to defeat Girag with "Number C39: Utopia Ray V".
Vector, who was believed to be dead, eventually emerged on Earth and used "Rank-Up-Magic Barian's Force" to brainwash Umimi Habara, who Dueled alongside her husband Tobio Habara against Yuma and Anna Kaboom. This ultimately failed as well.
Afterwards, Vector challenged Yuma to a Duel where he purposely lost and gave "Number 66: Master Key Beetle" to Astral while kidnapping "Ray Shadows". Yuma and the others headed to Sargasso to save Ray, where three of the Barian Emperors awaited. It was there that Ray revealed himself as Vector during his Duel with Yuma, emotionally breaking the latter and causing Astral to lose trust in him, resulting in the use of Dark ZEXAL.
Dark ZEXAL recklessly attacked Vector's "Number 104: Masquerade" with "Number C39: Utopia Ray V" equipped with "DZW - Chimera Clad", taking damage in the process thanks to Vector's "Hundred-Over". At the last minute, Yuma and Astral separated from Dark ZEXAL after they regained trust in one another. This renewed trust allowed them to merge into ZEXAL II and create "Rank-Up-Magic - Numeron Force" to Summon "Number C39: Utopia Ray Victory" and defeat Vector.
After Vector's Sargasso plan failed, he released Don Thousand and fused with him to begin searching for the Legendary Numbers.
Afterwards, he absorbed what remained of Dark Mist and used the power to create more Dimension-Fusing Devices in order to fuse the Human World with the Barian World.
He restored Mr. Heartland to his human form and reincarnated Kurage, as well as Semimaru and Kaninjaas Barians so Mr. Heartland could have underlings to assist him in defeating Yuma, Shark, and Kite. However, all but Mr. Heartland were defeat by Yuma, Kite, and Shark with the help of Trey, Quattro, and Quinton.
Later, Shark and Rio learned that they are really the two missing Emperors, Nasch and Merag. Dumon awakened their memories and transported them to Barian World, where they returned to their Barian forms.