The Short Answer: Warhammer 40,000 features three major allegiances fighting for control of the galaxy: the Imperium of Man, the forces of Chaos, and various Xenos (alien) races. Each faction has its own lore, visual identity, and playstyle. This guide breaks down the major factions so you know what each army brings to the tabletop.
The 41st Millennium is a dark and war-torn era. Humanity's vast Imperium stretches across the stars, locked in an endless struggle against corrupted traitors, daemonic forces, and alien threats. Every faction in Warhammer 40,000 brings its own flavor to the battlefield, from elite power armor squads to endless waves of melee infantry and devastating armored vehicles.
This guide provides a breakdown of the major factions across all three allegiances. We'll cover who they are, what drives them, and how they play on the tabletop. Use it as a reference to learn the galaxy's greatest armies.
Forces of the Imperium
The Imperium of Man is humanity's galaxy-spanning empire, united under the worship of the God-Emperor. For over ten thousand years, the Imperium has defended mankind against threats from within and without. Its military forces are vast and varied, ranging from superhuman warriors in power armor to massive regiments of ordinary soldiers backed by heavy weapons and armored vehicles.
Space Marines
Space Marines are the Imperium's elite fighting force. These genetically enhanced super-soldiers wear iconic power armor and wield the explosive bolters that have become synonymous with Warhammer 40,000. Space Marines are organized into Chapters, each with its own history, tactics, and culture. On the tabletop, they offer a balanced army that can adapt to most situations.
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Playstyle: Balanced, adaptable, elite infantry
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Strengths: Durable troops, strong shooting and melee, wide model range
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Best for: New players and veterans who want tactical flexibility
Notable Chapters include:
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Blood Angels – Specialize in fast assault and melee combat, known for their angelic imagery and tragic flaw
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Dark Angels – Secretive and tactically flexible, with strong Deathwing (Terminator) and Ravenwing (bike) units
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Space Wolves – Fierce warriors favoring close-range combat with a Viking-inspired aesthetic
Astra Militarum (Imperial Guard)
The Astra Militarum represents humanity's countless billions of regular soldiers. What they lack in superhuman abilities, they make up for in sheer numbers, heavy weapons, and armored vehicles. Expect infantry squads supported by battle tanks, artillery, and air support. This army rewards players who enjoy combined arms tactics and overwhelming firepower.
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Playstyle: Hordes of infantry backed by armored vehicles and artillery
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Strengths: Numbers, heavy weapons, tank squadrons
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Best for: Players who enjoy combined arms and large-scale warfare
Adeptus Mechanicus
The Adeptus Mechanicus worships the Machine God and maintains the Imperium's technology. Their forces blend flesh and machine, fielding cybernetic soldiers, walking robots, and arcane weaponry. On the tabletop, they offer strong shooting with unique support units that buff nearby allies.
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Playstyle: Shooting-focused with synergy buffs
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Strengths: Powerful ranged attacks, durable robots, tech-priest support
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Best for: Players who like synergy and a unique mechanical aesthetic
Adeptus Custodes
The Adeptus Custodes are the Emperor's personal bodyguards, each one a masterwork of genetic engineering. They field small, elite armies where every model hits hard and is difficult to kill. If you prefer quality over quantity, the Custodes deliver.
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Playstyle: Elite, low model count
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Strengths: Extremely tough, powerful in combat and shooting
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Best for: Players who want fewer models with maximum impact
Adepta Sororitas (Sisters of Battle)
The Adepta Sororitas are warrior nuns devoted to the Emperor's divinity. They combine faith-based abilities with solid shooting and aggressive melee infantry. Expect flamers, hymns that boost your units, and a model range full of gothic imagery.
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Playstyle: Aggressive mid-range with faith abilities
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Strengths: Flamers, strong infantry, Miracle dice mechanics
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Best for: Players who enjoy gothic aesthetics and risk-reward mechanics
Imperial Knights
Imperial Knights are towering war machines piloted by noble houses sworn to the Emperor. Each Knight is a centerpiece model that dominates the battlefield with heavy weapons and thick armor. They can be fielded as a standalone army or allied with other Imperium forces. This faction suits players who want a small model count with big impact.
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Playstyle: Low model count, high damage output
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Strengths: Massive firepower, tough armor, intimidating presence
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Best for: Players who want centerpiece models and fast painting projects
Other Imperium Factions
Several other forces fight for the Imperium:
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Grey Knights – Daemon-hunting Space Marines with powerful psychic abilities
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Deathwatch – Veteran Space Marines specializing in Xenos elimination
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Agents of the Imperium – Inquisitors, Assassins, and specialist operatives often allied into other armies
Forces of Chaos
Chaos represents the dark mirror of the Imperium. Ten thousand years ago, the Horus Heresy saw half of the Emperor's Space Marine Legions turn traitor, corrupted by the Ruinous Powers of the Warp. These Chaos factions now wage eternal war against humanity, empowered by daemons and dark gods. Chaos armies often blend corrupted power armor with daemonic mutations, offering aggressive playstyles with unique thematic twists.
Chaos Space Marines (Heretic Astartes)
Chaos Space Marines are the fallen brothers of the loyalist Chapters. These Heretic Astartes have spent millennia raiding Imperial space, their power armor scarred and twisted by Warp exposure. On the tabletop, they offer flexibility similar to loyalist Marines but with access to daemonic abilities, dark pacts, and corrupted war machines. They suit players who want a versatile army with a sinister edge.
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Playstyle: Flexible, aggressive, with daemonic support
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Strengths: Versatile units, access to dark pacts and daemon allies
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Best for: Players who want Space Marine tactics with a corrupted twist
Death Guard
The Death Guard are followers of Nurgle, the Chaos God of plague and decay. These corrupted Space Marines are bloated, rotting, and nearly impossible to kill. Their playstyle emphasizes durability and attrition, slowly grinding down opponents while shrugging off damage. Expect diseased infantry, toxic weapons, and models covered in grotesque detail.
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Playstyle: Slow, durable, attrition-focused
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Strengths: Hard to kill, toxic weaponry, strong in close quarters
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Best for: Players who like outlasting opponents
Thousand Sons
The Thousand Sons serve Tzeentch, the Chaos God of magic and manipulation. This army fields powerful psykers who can devastate enemies and manipulate their opponents' minds with sorcery. Their infantry are Rubric Marines, suits of armor animated by dust and bound souls. Choose the Thousand Sons if you want a psychic-heavy force with strong shooting.
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Playstyle: Psychic-focused with ranged firepower
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Strengths: Powerful sorcerers, mortal wound output, durable Rubric Marines
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Best for: Players who enjoy psychic phases and magical aesthetics
World Eaters
The World Eaters worship Khorne, the Blood God. Subtlety is not their strength. This army charges headlong into melee combat, seeking close-range carnage above all else. Berzerkers form the core of the force, supported by brutal characters and daemonic engines. World Eaters reward aggressive players who want to close the gap and fight in combat as fast as possible.
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Playstyle: All-out melee aggression
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Strengths: Devastating close combat, fast charges, relentless assault
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Best for: Players who want to get into melee and stay there
Other Chaos Factions
Additional forces serve the Ruinous Powers:
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Emperor's Children – Followers of Slaanesh, the Chaos God of excess, known for speed and sonic weaponry
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Chaos Daemons – Pure daemonic armies summoned from the Warp, aligned to one or more Chaos Gods
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Chaos Knights – Corrupted versions of Imperial Knights, towering war machines twisted by Chaos
Xenos Factions
The galaxy is home to countless alien species, each with their own agendas and enemies. These Xenos factions wage war against the Imperium, the forces of Chaos, and each other. For players who want something outside the Imperium vs. Chaos conflict, Xenos armies offer unique mechanics and striking model ranges.
Orks
Orks are brutal, green-skinned warriors who live for fighting. Their technology shouldn't work but somehow does, held together by collective belief and scrap metal. On the tabletop, Orks swarm the battlefield with hordes of infantry, ramshackle vehicles, and heavy weapons. They reward aggressive play and benefit from sheer numbers.
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Playstyle: Horde army with aggressive melee and shooting
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Strengths: Numbers, tough infantry, chaotic vehicle options
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Best for: Players who enjoy swarm tactics and unpredictable fun
Tyranids
Tyranids are an extragalactic swarm of alien predators that consume all organic matter in their path. Their forces range from small, skittering creatures to massive bio-titans. Tyranids excel at melee combat and overwhelming opponents with endless waves of monsters. This army suits players who enjoy fast, aggressive tactics.
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Playstyle: Swarm or monster-heavy melee aggression
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Strengths: Fast units, powerful monsters, synapse buffs
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Best for: Players who want to overwhelm opponents with alien horrors
Necrons
Necrons are ancient machines that once ruled the galaxy. After millions of years in slumber, they now awaken to reclaim their empire. Their forces feature durable infantry, powerful vehicles, and the ability to regenerate fallen models. Necrons offer a resilient army with strong shooting and iconic Egyptian-inspired aesthetics.
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Playstyle: Durable, mid-range shooting with reanimation
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Strengths: Hard to kill, strong firepower, resurrection mechanics
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Best for: Players who like resilient armies with a unique visual style
Aeldari (Craftworlds and Drukhari)
The Aeldari are an ancient, dying race split into factions. Craftworld Aeldari field fast, specialized units with powerful psykers and advanced technology. Drukhari (Dark Eldar) are their cruel kin, raiding realspace for captives to fuel their dark needs. Both armies emphasize speed and hitting power but require careful positioning to avoid losses.
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Playstyle: Fast, fragile, high damage output
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Strengths: Speed, powerful psykers (Craftworlds), deadly raiders (Drukhari)
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Best for: Experienced players who enjoy glass cannon tactics
T'au Empire
The T'au Empire is a young, technologically advanced civilization that fights for the "Greater Good." Their armies rely on powerful ranged firepower, battlesuits, and support units rather than melee combat. T'au reward players who enjoy shooting phases and careful target priority.
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Playstyle: Shooting-focused with battlesuit support
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Strengths: Long-range firepower, powerful battlesuits, synergy bonuses
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Best for: Players who prefer ranged combat over melee
Leagues of Votann
The Leagues of Votann are a newly returned faction of abhuman spacefaring clans. They field compact, durable infantry and powerful vehicles with advanced weaponry. This army offers strong shooting and resilience in a tight, elite force.
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Playstyle: Elite shooting with durable infantry
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Strengths: Tough units, strong ranged output, Grudge mechanics
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Best for: Players who want a compact, hard-hitting army
Genestealer Cults
Genestealer Cults are insidious uprisings seeded by Tyranid infiltrators. Their armies blend corrupted civilians, mining equipment, and ambush tactics. They excel at surprise attacks and board control, rewarding tricky, tactical play.
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Playstyle: Ambush and board control
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Strengths: Deep strike, cheap infantry, surprise deployment
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Best for: Players who enjoy outmaneuvering opponents
Other Xenos Factions
A few other alien forces appear on the battlefield:
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Harlequins – Aeldari performers and warriors known for speed, acrobatics, and close combat
Building Your Army
Warhammer 40,000 offers a faction for every taste and playstyle. The Imperium fields humanity's defenders, from elite Space Marines to the endless ranks of the Astra Militarum. Chaos brings corrupted traitors and daemonic forces twisted by the Warp. Xenos armies let you command alien hordes, ancient machines, or technologically advanced empires.
Each faction has its own codex rulebook with full details on units, abilities, and lore. Combat Patrol boxes provide a solid starting point for any army, giving you a ready-to-play force at a great value. From there, expand your collection based on what catches your eye and fits how you want to play.
Looking to start or grow your Warhammer 40,000 army? On-Board Gaming carries miniatures, codex rulebooks, paints, and hobby supplies from Games Workshop. Stop by our Escondido store to browse our selection, get painting tips, or join our regular gaming events. For more on getting started, check out our guide on How to Get into Warhammer 40k.
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