Aqir

The aqir (pronounced "UH-keer") are an ancient, sentient insectoid race who—much like the n'raqi—arose from the organic matter seeping from the Old Gods' massive bulks during the primordial era of Azeroth. When the Old Gods' Black Empire was defeated by the titan-forged, the aqir were driven underground, where they remained until they were reawakened by Kith'ix millennia later. Obsessed with eradicating all non-insectoid life on Kalimdor, they waged war against the trolls, but were eventually defeated and split into three distinct colonies: the nerubians of Azjol-Nerub, the qiraji of Ahn'Qiraj, and the mantid of Manti'vess. Armies of the original aqir race reemerged thousands of years later in service to the newly-freed Old God N'Zoth.

The Black Empire
After the Old Gods embedded themselves in the surface of primordial Azeroth, they soon began spreading corruption around them, blighting and withering the land. The organic matter that seeped from their massive bodies gave rise to two distinct races: the aqir and the n'raqi (or "faceless ones"). The incredibly strong and resilient aqir were employed as laborers by the cunning and intelligent n'raqi and were forced to build temple cities and towering citadels around their masters' massive bulks. The greatest of these holdings was built around the most powerful of the Old Gods, Y'Shaarj, and this civilization soon spread across Azeroth, forming the Black Empire.

However, one day the titan-forged, servants of the titan Pantheon, arrived on Azeroth to combat the Black Empire. The titan-forged were successful in imprisoning the enslaved Elemental Lords and thereafter turned their attention to the aqir, many of which dwelled in enormous catacombs below the surface of the empire. The titan-forged Archaedas used his earth magic to collapse the burrows, forcing the insectoids to escape above ground, where they found themselves surrounded by the titan-forged. Most of the aqir were destroyed by the titan-forged, though several small pockets survived by tunneling deep underground, too weakened to launch a counterattack.

War with the trolls
Thousands of years later, long after the Black Empire's fall, a race known as the trolls rose to prominence in Kalimdor and established great civilizations that covered most of the continent. One day, roughly 16,000 years before the First War, a rebellious group of trolls accidentally awakened Kith'ix, an ancient servant of the Old God Yogg-Saron who had survived an encounter with the titan-forged Tyr centuries earlier. Kith'ix, knowing that destroying the trolls would please its Old God masters, reached out with its mind and discovered the aqir, rallying them into building the subterranean empire of Azj'Aqir. When the time was right, Kith'ix led the aqir to the surface, launching a terrible war against the trolls.

The aqiri threat was unlike anything the trolls had ever faced before. When the insectoids had almost reached the sacred Zandalar Mountains, the Zandalar tribe united the trolls into the Empire of Zul to fight back against the legions of Azj'Aqir. Ambush tactics and the aid of the Wild Gods helped the trolls in pushing back the insectoids and even wounding Kith'ix, who retreated with a group of its closest followers to the northeastern corner of the continent. Knowing that the aqir would soon move to attack outlying troll territories and would simply burrow underground and establish new colonies if allowed to live, the Zandalari sent the powerful Amani, Gurubashi and Drakkari tribes to track down and eliminate the insectoids, as well as establish new strongholds to guard the distant corners of the troll empire. The Drakkari overthrew the northern aqir, who had enslaved a group of titan-forged tol'vir known as obsidian destroyers, while the Gurubashi succeeded in containing a group of aqir in the titan-forged prison complex of Ahn'Qiraj through a war of attrition. In the northeast, the Amani succeeded in tracking down and killing Kith'ix before establishing the city of Zul'Aman over its corpse.

During the war the aqir ravaged the jungle of Vol'dun near the Zandalar Mountains, transforming it into a desert.

With Kith'ix dead, the trolls eventually managed to shatter Azj'Aqir. Having successfully eradicated all aqiri presence from central Kalimdor and contained the insectoids in the far northern and southern reaches of the continent, the trolls proclaimed themselves victorious.

The three empires
Three distinct groups of aqir managed to survive the destruction of their empire. The ones in the north congregated around the underground prison of the Old God Yogg-Saron, evolving into the nerubian race and establishing the kingdom of Azjol-Nerub. The ones in the southwest remained inside Ahn'Qiraj, where the energies of the Old God C'Thun warped them into a race known as the qiraji. During the later stages of the war, one group had also fled to the southeast. Drawn towards the lingering energies of the dead Old God Y'Shaarj, these aqir took up the name mantid and founded the colony of Manti'vess.

Battle for Azeroth
Shortly after the Great Sundering, the surviving aqir known as Zek'voz arrived on Zandalar—now turned into an island—in order to bring the newly-isolated Zandalari trolls into the service of his master N'Zoth. However, he was not prepared to encounter the titanic defenses of Uldir and ended up being captured, studied, and finally stored in the Archives of Eternity.

When adventurers delved into Uldir in order to stop the rise of G'huun, they encountered and slew Zek'voz, who summoned various Old God servants from his people's successor races.

Visions of N'Zoth
It was assumed that the aqir had been driven to extinction at the end of their war with the trolls, but it seems instead that they were rebuilding. When N'Zoth was freed from its prison, its aqiri servants were unleashed upon Azeroth under the command of the Hivemind. The insectoids are now among N'Zoth's Black Empire forces from the realm of Ny'alotha. Aqir are unearthed in the Assault in Uldum.

As a mount

 * Shadowbarb Drone is a quest reward from Ready to Fly.
 * Malevolent Drone has a chance to drop from Corpse Eater.
 * Wicked Swarmer can be purchased from Wrathion in the Chamber of Heart at a cost of.

As a companion pet

 * Aqir Hivespawn and Ra'kim have a chance to drop from the Hivemind in Ny'alotha, the Waking City.
 * Black Chitinous Plate has a chance to drop from Skikx'traz.
 * Shadowbarb Hatchling is a reward from They Grow So Fast.
 * Stinky Sack has a chance to drop from Lord Aj'qirai.

As a hunter pet
Aqiri are a family of Exotic Beasts added in patch 9.0.1 as a replacement for the silithid family. Despite the name, the only aqir who are tamable as part of this family are the large aqir goliaths. The family also includes silithid reavers, workers, and colossi, kunchong, and sand reavers.

Aqir scarabs and winged aqir are tamable as part of the beetle and wasp families, respectively.

Trivia

 * The adjectival demonym of "aqir" is "aqiri".
 * If aqir eggs are laid inside a corpse, it causes the corpse to become a bloated zombie.
 * Aqir are carnivores and eat sapient races, including even fellow creations of the Old Gods like n'raqi and k'thir. However, eating other aqir (as well as aqir offshoots like mantid) makes them sick.
 * An Ancient Aqir Artifact could drop from Zul'jin in Zul'Aman, while Crystal Aqiri Skull can be looted from the Treasure Piles that spawn after defeating Opulence in the Battle of Dazar'alor.
 * The Scepter of Azj'Aqir is a rare tol'vir archaeology artifact. Though it shares the name with the ancient aqiri empire, it is actually named for a tol'vir sorcerer of the same name. Given that the item also uses "Qiraj" as a demonym instead of "Qiraji," and the other item descriptions have nothing to do with the tol'vir, this may be an error.
 * Nerubians reminded Sylvanas Windrunner and Lady Liadrin of tales of the aqir.
 * According to a journal entry by Brann Bronzebeard, titan records suggest that the Old Gods created the aqir out of something that was not the silithid or generic insects (as those are descended from the aqir). This "something" was later stated to be some kind of species of various "proto-insectoid humanoids" that were part of the "Black Empire." This theory was later proven wrong, as the Old Gods actually gave rise to the aqir directly alongside the n'raqi.
 * Zek'voz's model is called aqir.m2 in the files, though he is never called an aqir in-game. His race was confirmed when other aqiri mobs with identical and similar models were introduced in patch 8.3.0.
 * In a hotfix a couple weeks after patch 8.3.0, a number of aqir in Uldum were reclassified from aberrations into humanoids and beasts.
 * HS Malevolent Strike card art has aqir in Hearthstone.