The first question most newcomers ask about Warhammer 40,000 is simple: what are all these factions, and how do they fit together? The list can look overwhelming, but it becomes much easier once you know that almost every army belongs to one of three broad groups: the Imperium of Man, the forces of Chaos, and the alien races known collectively as Xenos.
This guide answers that one question. It won't tell you which army is strongest (that changes with every rules update), but it will show you who everyone is, in one place.
The setting in two sentences
Warhammer 40,000 takes place in the 41st and 42nd millennia, in a galaxy at endless war. Humanity's vast, decaying Imperium is besieged on every side by traitors who worship the Chaos Gods and by alien species with their own ancient agendas.
The three big groups
- Imperium: the armies of humanity and its loyal servants, from ordinary soldiers to genetically engineered Space Marines and giant war machines.
- Chaos: humans and Space Marines who turned traitor, plus the daemons of the Warp they serve.
- Xenos: the alien races, each with its own goals. They are not allies of one another; most of them fight everyone.
Every faction at a glance
The table below follows the faction list in the official Warhammer 40,000 points document at the time of writing (October 2026). The giant Titan Legions and Chaos Titan Legions are left out because they are a specialist, large-scale option rather than a starting army.
| Group | Faction | In one line | How it looks on the table |
|---|---|---|---|
| Imperium | Space Marines | Genetically enhanced super-soldiers organised into Chapters | Power armour in hundreds of Chapter colour schemes |
| Imperium | Blood Angels, Dark Angels, Space Wolves, Black Templars, Deathwatch | Space Marine Chapters (and one specialist order) with their own army rules | Red, dark green, blue-grey, black-and-white, and black with Chapter shoulder pads |
| Imperium | Grey Knights | Psychic daemon-hunting Space Marines | Silver armour and ornate weapons |
| Imperium | Adeptus Custodes | The Emperor's personal guardians | Gold armour and red cloaks |
| Imperium | Adepta Sororitas | Warrior nuns of the Imperial church | Armour, robes and flames |
| Imperium | Adeptus Mechanicus | Tech-priests and their cybernetic soldiers | Red robes, bionics and strange weapons |
| Imperium | Astra Militarum | The Imperial Guard: billions of ordinary human soldiers and tanks | Uniforms, flak armour and armoured vehicles |
| Imperium | Imperial Knights | Noble houses piloting walking war machines | Heraldic colours on towering Knights |
| Imperium | Imperial Agents | Inquisitors, assassins and other specialist servants | A mix of characters and small units |
| Chaos | Chaos Space Marines | Traitor Space Marines who fell to Chaos | Corrupted power armour, spikes and icons |
| Chaos | Death Guard | Traitor Space Marines devoted to Nurgle, god of decay | Rotting, pallid armour and plague weapons |
| Chaos | Thousand Sons | Sorcerous traitors devoted to Tzeentch | Blue and gold armour |
| Chaos | World Eaters | Berserk traitors devoted to Khorne | Red and brass armour |
| Chaos | Emperor's Children | Traitors devoted to Slaanesh and excess | Pink and purple, with ornate details |
| Chaos | Chaos Daemons | The daemons of the four Chaos Gods themselves | Monstrous, brightly coloured creatures |
| Chaos | Chaos Knights | Corrupted walking war machines | Dark, spiked Knights |
| Xenos | Necrons | Ancient undying robots waking from a 60-million-year sleep | Metal skeletons with glowing weapons |
| Xenos | Tyranids | A galaxy-devouring swarm controlled by the Hive Mind | Carapace and skin in hive fleet colours |
| Xenos | Orks | Brutal, cheerful greenskins who live for battle | Green skin, scrap armour and clan colours |
| Xenos | Aeldari | An ancient, dwindling psychic race | Sleek armour and grav-tanks |
| Xenos | Drukhari | Cruel raiders from a hidden city | Spiked armour and fast skimmers |
| Xenos | T'au Empire | A young, expanding empire with advanced technology | Battlesuits and clean, angular armour |
| Xenos | Genestealer Cults | Hidden human cults infected by Tyranid influence | Industrial workers with alien features |
| Xenos | Leagues of Votann | Stout, clone-born miners and warriors with advanced technology | Armoured warriors and heavy machines |
Why so many Space Marine entries?
Space Marines are the face of Warhammer 40,000, so the game gives several of their most famous Chapters their own army rules. Blood Angels, Dark Angels, Space Wolves and Black Templars are all Space Marines, just with distinct histories, units and colours. If you want to understand where those Chapters come from, read our guide to Space Marine Chapters.
Can different factions be allies?
Within a group, sometimes. Imperial armies often fight alongside each other in the background, and Chaos warbands can include daemons. The Xenos are different: Necrons, Tyranids, Orks and Aeldari have nothing in common except that they are not human. Treat the "Xenos" label as a convenient shelf, not a team.
How to choose your first faction
Forget about rules strength and ask yourself three questions instead:
- Which models do you love looking at? You will spend hours painting them, so this matters most.
- Do you want a few elite models or a big horde? Custodes and Space Marines field small, powerful armies; Orks, Tyranids and the Astra Militarum field many more models.
- Which story grabs you? Noble defenders, fallen heroes, ancient robots or an unstoppable swarm? Lore keeps you motivated through a long painting queue.
How the factions differ to paint
Painting difficulty depends more on your approach than on the faction, but some general patterns help:
- Quick to get looking good: Necrons and other heavily metallic armies respond well to drybrushing and washes. Our Necron painting guide shows how.
- Big, clean surfaces: Space Marines, Custodes and T'au have smooth armour panels that are forgiving for learning layering and edge highlights.
- Lots of models: Orks, Tyranids and the Astra Militarum reward fast, repeatable methods rather than detailing every model.
A note on keeping up to date
Games Workshop adds and adjusts factions over time, and the story moves on with each new edition. This list reflects the official faction list as of October 2026. If something has changed since, the background of each army will still hold true even if its rules have shifted.
Quick summary
- Every army belongs to the Imperium, Chaos or the Xenos.
- Several Space Marine Chapters have their own army rules, which is why the list looks longer than it really is.
- Choose your first army by models and story, not rules strength.
Independent resource published by Blubbercove Ltd. This page is not affiliated with, sponsored by, endorsed by, authorised by or licensed by Games Workshop Limited.
Warhammer 40,000 and the names of all associated armies, characters, races, vehicles, units and places are trademarks of Games Workshop Limited, used here without permission and solely to identify the subject. This is an unofficial fan guide.