[Edit]
Factions to which Operators in Arknights are affiliated/aligned with as displayed in-game and their branches if applicable.
Do note that a displayed faction is not always fully indicative of an Operator's current affiliation/allegiance as the stories of Arknights continue to develop.
Attention!
The descriptions of each faction are unofficial and intended to provide readers with a quick introduction to each faction.
Terra
 |
Ægir A technologically-advanced nation dwelling beneath the waves, conventionally outclassing most other nations of Terra in all but the most esoteric weaponry. Once an ally of Iberia, the Profound Silence broke their ties and signaled the start of Ægir's isolationism. Even as they continue to be plagued by the Seaborn in a never-ending, escalating battle for survival, Ægir remains silent.    
| ||
 |
Abyssal Hunters The result of Ægir's continuous fight against the Seaborn, the Abyssal Hunters are the best of the best. With strength and resilience far beyond the average Terran and the ability to breathe and fight underwater with ease, they are forces of nature upon the battlefield.      
| ||
 |
Babel The fallen predecessor to Rhodes Island Pharmaceuticals, Babel was led by the exiled Sarkaz King Theresa, who attempted to break through the suffering that envelops Terra. Though toppled through shadowy circumstances resulting in Theresa's death, Babel's founding ideals live on through Rhodes Island.    
| ||
 |
Bolívar Bordering Columbia and Sargon, Bolívar is rich in natural resources and Originium deposits—but is scarred by war and instability. Originally founded as an Iberian colony, Bolìvar has long since gained independence, but has been the target of numerous superpowers seeking control of the region's plentiful resources through espionage and the establishment of puppet governments. Currently, Bolívar is locked in a three-way civil war that has fallen into a stalemate.       
| ||
 |
Columbia Once a colony of Victoria, the Columbian Union gained its independence and pushed ahead to become Terra's youngest superpower. Leading the charge in scientific advancement and barrenlands exploration, Columbia has already contributed greatly to Terra's development despite its young age.                         
| ||
 |
Blacksteel Worldwide A private military company tied to the Columbian government, Blacksteel operates from their landship headquarters, Fort Barron—the largest landship on Terra. Blacksteel Worldwide's well—equipped professional mercenaries, while still serving the national interests of Columbia, will work for the highest bidder.       
| ||
 |
Rhine Lab Columbia's most successful scientific institute, Rhine Lab is the epitome of cutting-edge technology and is greatly admired by aspiring researchers. Despite scandals and shady practices, Rhine Lab remains a staunch juggernaut within Columbia's scientific sector.            
| ||
 |
Siesta An independent city-state who willingly submitted themselves to Columbia's jurisdiction, Siesta is a famous tourist destination known for its pristine beach and the annual Obsidian Festival. Once sedentary, a natural disaster forced Siesta to successfully convert into a nomadic city.    
| ||
 |
Followers A small team of wandering medics created by Shining consisting of her, Nightingale, and later Nearl. Eventually became an independent branch of Rhodes Island and provides assistance to field operators when available.   
| ||
 |
Higashi A nation of the eastern world once known for its mystical religion surrounding the goddess Asayo-Yoruakeru, Higashi has been subjected to decades of bloody and brutal civil war. After the warring nation successfully banded together to resist an Ursine military invasion, an uneasy truce ushered in twenty years of a fragile peace between the traditionalist North and the modernizing South.            
| ||
 |
Iberia The seafaring nation of Iberia once knew ample delights and great riches—before the Profound Silence put an end to their prosperity, sinking much of the country into the ocean and leaving Iberia isolated and broken. The Inquisition has taken control of the nation and works tirelessly to pick up the pieces, but Iberia's future remains uncertain.          
| ||
 |
Kazimierz The land of knights, Kazimierz, has undergone drastic changes—transforming from a land of traditional chivalrous values to one of corporations and bloodsports. These changes have introduced a substantial class divide between the nomadic corporate megacities and small, sedentary towns.        
| ||
 |
Pinus Sylvestris Knightclub A Kazimierzian knightclub consisting of disgraced Infected knights. Lead by the Flametail Knight Sona, Pinus Sylvestris fights back against Infected discrimination perpetrated by the corporations.     
| ||
 |
Kjerag A relatively small theocracy residing on Mount Karlan, the tallest mountain on Terra. The people of Kjerag are known for the worship of Kjeragandr, the nation's goddess who blesses the nation and keeps Kjerag a Catastrophe-free land. Nevertheless, the modern age has forced Kjerag to end its centuries-long isolationism, and the nation is rapidly catching up to Terra's superpowers utilizing the industrialization they long resisted.       
| ||
 |
Karlan Trade CO., LTD A Kjeragian national corporation led by Enciodes SilverAsh dedicated to the modernization of Kjerag. Karlan Trade has immense power and plentiful connections within the nation, and also enjoys a good relationship with Rhodes Island.     
| ||
 |
Laterano The Holy City of the Sankta is the nation of desserts, firearms, pranks, and religion. While its unique culture feels strange to outsiders, Laterano has remained steadfast in the face of many geopolitical conflicts throughout the centuries. The Holy City has also established itself as international peacekeepers and seeks to bring lasting peace through the "Summit of Nations."               
| ||
 |
Leithanien The nation of spires, Leithanien is famous for their many academies dedicated to the comprehensive study of Originium Arts and music. The nation has long since suffered from the reign of the mad Witch King, and his recent death heralds a new age with the ascension of the Twin Empresses.           
| ||
 |
Minos A confederacy of three city-states united through the religious worship of their heroes, Minos is one of the few longstanding nations to endure since ancient times. Famous for their warrior culture and high-quality weapons, Minos is a well-regarded nation of art and a popular tourist destination, but has an unsettled score with the neighbouring Sargon that once colonized Minos for a century.     
| ||
 |
Rhodes Island Rhodes Island Pharmaceuticals, frontrunner in Oripathy treatment and education—and an object of great interest to many political entities due to the organization's involvement in multiple exceptionally significant events. Through an inclusive and indiscriminate hiring process, Rhodes Island's landship of the same name is home to both Infected and uninfected from all walks of life.                                                     
| ||
 |
Rhodes Island-Elite Operator Rhodes Island's special forces—consisting of distinguished and powerful individuals wholly devoted to Rhodes Island's cause. Most of the original members were part of Babel and remained with Rhodes Island.      
| ||
 |
Op Team A4 A squad serving Rhodes Island, consisting of veteran fighters taking a behind-the-scenes approach as opposed to active combat.      
| ||
 |
Reserve Op Team A1 A Reserve squad consisting of trainees. The members of A1 are close friends who joined Rhodes Island from Tkaronto, Columbia.     
| ||
 |
Reserve Op Team A4 A reserve squad consisting of younger, teenage members. Due to their age, they see little to no active combat.     
| ||
 |
Reserve Op Team A6 A Reserve squad of civilians that sees no combat, instead performing clerical work aboard Rhodes Island while being taught self-defense.     
| ||
 |
S.W.E.E.P. The Special Warrant Extermination and Elimination Protocol is Rhodes Island's secret counterintelligence unit founded by Kal'tsit after Babel's fall, responsible for protecting Rhodes Island from spies and turncoats. All information on S.W.E.E.P. is restricted to Rhodes Island's highest administration.   
| ||
 |
Rim Billiton A nation formed by various mining corporations to protect their interests from foreign influence, avoiding Bolívar's fate. Rim Billiton's close-knit mining communities with a primarily Cautus population have resisted the traditionally stronger superpowers of Terra, controlling the flow of their resources from the abundant Targangils Prime Vein.            
| ||
 |
Sami A tribal nation that practices animism and the worship of nature, Sami's mysterious culture remains mostly unaffected by the outside world. Wary and distrustful of outsiders, the people of Sami resolutely guard Terra's north from the approaching terror encroaching on the Infy Icefield.      
| ||
 |
Sargon The Sargon Empire is an ancient monarchy ruled by the Aslan Shahanshah—the "King of Kings"—whose absolute sovereignty stretches from the desert clans of the west to the untouched tribes of the eastern tropical rainforest. Often ignorantly regarded as the oldest nation on Terra, Sargon has long suffered from internal factionalism caused by tribalism and foreign intervention. Despite this, Sargon's elite imperial forces stand guard over the uninhabitable Foehn Hotlands, where a grand battle against otherworldly threats once occurred in ages past.                     
| ||
 |
Siracusa The nation of rain and mafioso, formerly an autonomous Kreis of Leithanien. Siracusa gained its independence from Leithanien, but fell into decades of anarchy caused by the many famiglie until their eventual submission to Signora Sicilia, who united them under the Lateran faith and strict laws.             
| ||
 |
Chiave's Gang A companion group formed by its leader Chiave, seeking asylum on Rhodes Island after being driven out of Siracusa after crossing several prominent mafia famiglie.   
| ||
 |
Ursus The Empire of Ursus was born from the violent toppling of the Elder Hippogryph by the Ursi populace and expanded its borders in the frigid north through unrestrained militarism. The brutal military of Ursus cemented the empire as an indisputable superpower through an opressive regime, but a failed invasion of Higashi and a devastating civil war plunged Ursus into political turmoil that persists to this day.     
| ||
 |
Ursus Student Self-Governing Group (U.S.S.G.) A group of traumatized students from Chernobog who survived the Chernobog Crisis after being locked inside of their school by a sociopathic Reunion commander. The U.S.S.G. now lives aboard Rhodes Island, recieving treatment and education.     
| ||
 |
Victoria One of Terra's strongest superpowers, the Victorian Empire is a hegemonic empire ruling over the most fertile land on Terra, enabling Victoria as the leader of the modern revolution, bringing industrialization and cultural reforms. A classical monarchy once ruled by the Draco and Aslan dynasties, the Victorian throne has been vacant for decades since the public revolt and execution of King Alistair II, leaving the Eight Grand Dukes to rule over Victoria until a new king is crowned.                               
| ||
 |
Glasgow A street gang who once called Londinium home, led by "the Siege", Alexandrina Vina Victoria, the exiled princess in hiding and rightful heir to the vacant Victorian throne.    
| ||
 |
Tara Once an ancient monarchy led by a Draco tribe seeking to retain their pastoral culture, Tara was forcefully annexed by its kin ruling Victoria centuries ago. In the modern day, Tara's remnants strive to preserve their lost culture and restore their independence. Despite their progress, the region remains highly contested and their independence unrecognized by the Victorian authorities.    
| ||
 |
Yan The indisputable superpower of the eastern world, the Empire of Yan rules over the descendants of the Hundred Clans under a dynasty led by the True Lung. While famous for its unique culture unfamiliar to the western world, Yan wields great military might—having once challenged the godlike Feranmuts through the Great Hunt, cementing Yan's prosperity and sovereignty for ages to come.                
| ||
 |
Yan-Sui A mighty yet arrogant Feranmut who once allied with the mortals of Yan to expel Its kin during the Great Hunt, Sui was later subjugated by the Yanese emperor, who entombed the Feranmut within a grand, hidden mausoleum. While It remains dormant, Its consciousness has shattered into twelve distinct humanoid avatars who see each other as siblings.      
| ||
 |
Yan-Lungmen A Yanese autonomous district ruled by Wei Yenwu. A bustling special economic zone with a unique culture, Lungmen is also Yan's main point of contact with many of the western nations of Terra.        
| ||
 |
Lee's Detective Agency (L.D.A.) The home of Mr. Lee and his found family. A well-connected odd jobs business residing in Lungmen.    
| ||
 |
Lungmen Guard Department (L.G.D.) Lungmen's local police force and military, formed of various departments dedicated to the defense and security of Lungmen.    
| ||
 |
Penguin Logistics A straightforward logistics company run by Emperor, Penguin Logistics is famous in Lungmen and beyond for their iconic employees and unique, destructive style.      
| ||
Non-Terra
|
Ave Mujica An all-girl Gothic rock musical band from Earth originating from the disbanded CRYCHIC, all five members have learned to work together on stage despite their differences.     
| ||
|
Laios's Party A dungeoneering team from the "Dungeon World" seeking a lost teammate. Using their experiences inside the mythical Dungeon, they create dishes out of the various monsters inhabiting the land of Terra as they explore the world.    
| ||
 |
Team Rainbow An elite counterterrorism unit from Earth led by the enigmatic "Six" and formed by some of the world's top intelligence agents and militants. Members of Team Rainbow have found themselves trapped on Terra, and are independently exploring the land to find a way back to their own world with assistance from Rhodes Island.        
| ||
Night-scouring Gleam