Warhammer 40k: Chaos Space Marines 9th Edition guide

Warhammer 40k's Chaos Space Marines wreak havoc from the Eye of Terror across the galaxy - here's our guide to lore, tactics, and collecting

Warhammer 40k Chaos Space Marines faction guide Warhammer Community artwork showing a chaos space marine swinging an axe

The universe of Warhammer 40,000 isn’t just filled with those fighting desperately against the encroaching tide of Chaos, such as the Imperium or the Eldar. Some Warhammer 40k armies – like the infamous Chaos Space Marines (a.k.a. Heretic Astartes) – choose to fight for it.

Chaos, in the 41st millennium, throws a wide net over malcontents, wizards, heretics, and many others who choose to throw their lot in with dark gods. Some come to Chaos to learn forbidden knowledge, others for power, others for freedom from restrictive rules. No-one is immune to the siren song of Chaos – not even, of course, the Imperium’s elite guardians: the Space Marines.

Chaos Space Marines have been a staple of the setting going all the way back to the original Adeptus Titanicus board game. Legend has it the original version of this titanic battling game would have contained Imperium titans facing off against their Eldar counterparts but an issue with the models saw the Eldar being dropped from the box at the last minute. A hasty bit of rethinking and retooling, along with some new lore, saw the idea of a schism in the Imperium being born. This allowed the box to contain two sets of human-style titans, with one set belonging to the traitorous forces of Horus and his heresy.

Whatever their beginnings, Chaos Space Marines have become one of the most well represented forces in Warhammer 40k. From the tabletop to fiction, the superhuman power-armoured warriors of Chaos have become almost as iconic as their imperial counterparts.

We invite you to delve into the darker side of the Warhammer 40,000 universe with us and learn just who the Chaos Space Marines are, where they come from, and how they play on the tabletop battlefield.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community artwork showing the Primarch Fulgrim and his legion, the Emperor's Children, before the Horus Heresy

Chaos Space Marines lore

Chaos itself has existed in the setting as long as sentient beings have drawn breath, but for Chaos Space Marines we have to look instead to three select individuals: the Emperor, Horus, and Lorgar.

Horus was the fulcrum around which the Chaos Space Marines pivoted from loyalty to heresy

The Emperor is responsible for creating all Space Marines and their genetic fathers, the Primarchs, so will always be partially behind the creation of Chaos Space Marines. It does appear, especially with some revelations in some of the novels, that the rot which led many Space Marines to the dark side set in exceedingly early. Humanity’s Emperor may have gained some of the powers and knowledge he used to create the Primarchs from the Chaos Gods themselves – meaning that the fall of many legions of Space Marines may have been inevitable right from the start. Horus was the fulcrum around which the Chaos Space Marines pivoted from loyalty to heresy. He was the Warmaster of all Space Marines until a combination of hubris, plotting, and a magic knife led him to the welcoming arms of Chaos. His fall led many other legions to go with him, either manipulated to Chaos’ side, or drawn through promises of power beyond imagination, more often than not aided by Primarchs’ simple hatred of the Emperor himself.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community graphic showing the icon of the Word Bearers Legion

The final architect of the Horus Heresy and the Space Marines’ fall to Chaos was the Primarch of the Word Bearers, Lorgar. A religious zealot who worshipped the Emperor as a god, he redirected his faith to an older power when his fervour was rebuffed by the Master of Mankind. This saw him embrace Chaos earlier than any of the other Primarchs, leading him to begin seeding traitors throughout his brothers’ legions. It was one of these, Erebus, who oversaw the final corruption of Horus, leading the way to over ten thousand years of endless war.

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Other Primarchs joined the ranks of Horus and Lorgar: Magnus and his Thousand Sons; Angron and the World Eaters; Alpharius of the mysterious Alpha Legion; Fulgrim and his perfection-seeking sons, the Emperor’s Children; Perturabo and the Iron Warriors; Konrad Curze of the Night Lords; and, finally Mortarion of the Death Guard.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community artwork showing The Emperor fighting Horus aboard the Vengeful Spirit

Unfortunately for Horus, his uprising did not go quite according to plan. Though he struck down the loyalist Primarch Sanguinius, of the Blood Angels – and dealt a mortal blow to the Emperor – Horus himself was slain, and his fleets and legions splintered, unable to overcome Earth’s defences. Fleeing into the Eye of Terror, a giant rent in reality caused by the fall of the Aeldari Empire, the traitors escaped the loyalists’ wrath, and continue to plot, plan, and lick their wounds, waiting for a time they will be able to wreak revenge on the Imperium once again.

You want it darker

You want it darker

If you want to take a step further into the realm of Warhammer 40k’s dark gods, why not learn where it all began with our Horus Heresy reading order or delve into all the ruinous powers' adherents in our Warhammer 40k Chaos factions guide.

Though unity has long since fled the Chaos Space Marines (many legions are now little more than pirates or raiders) they still occasionally work together under the direction of the new Warmaster; Abaddon the Despoiler. He and his Black Legion make the core of the blade forever pointed at the throat of humanity, and many Black Crusades have spilled forth from the Eye of Terror to bring ruin to the Imperium under Abaddon’s banner.

Now, in the closing years of the 41st Millennium, the Chaos Space Marines are beginning to reclaim the galaxy little by little. Cadia, the bastion world guarding the Eye of Terror, has fallen, and a vast storm of warp energy has ripped the galaxy in two. This is a time of instability – and it’s a time that Abaddon hopes will see Chaos Space Marines become ascendant over the slowly wasting Imperium.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community artwork showing Abaddon the despoiler leading the Black Legion in battle

Who are the Chaos Space Marines Characters?

With lore stretching back to the early days of Warhammer 40,000, and many books and releases behind them, there are plenty of Chaos Space Marine characters to choose from. If you’re looking for inventive models that stretch the definition of a Space Marine, you’re looking in the right place. Let’s meet the gang.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community photo showing Abaddon the Despoiler's model for Warhammer 40k

Abaddon the Despoiler

When Horus fell, it was a time of great despair for all Chaos Space Marines – and none felt that despair more keenly than his own legion, the Sons of Horus. Eventually they managed to reform through strength of will alone, and that strength came from one of the Sons of Horus’ most powerful and fearsome warriors: Abaddon. Blessed by all four Chaos Gods but loyal to none, he leads the reborn and remixed Sons of Horus – now known as the Black Legion and incorporating parts of all traitor legions – in a never-ending crusade against the Imperium. Unlike many Chaos Space Marines, Abaddon the Despoiler doesn’t truly believe in Chaos; he is motivated purely by his great hatred for the Emperor and all those loyal to Him.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community artwork showing Fabius Bile collecting samples

Fabius Bile

While Fabius Bile is certainly a Chaos Space Marine (he was one of the Emperor’s Children legion after all), he has long since strayed from any one legion. Devoted to nothing but his own perverted ideal of perfecting Space Marine flesh, he has become a chirurgeon and scientist without peer, mainly because he’ll conduct experiments no sane person would dare consider. He travels throughout the known galaxy, always seeking to create a new version of the Space Marine – one better, faster, stronger, more adaptable. With the rise of Primaris Space Marines, he may now have all the new material he’ll ever need to twist Chaos Space Marines into new forms, finally perfecting his life’s work.

Huron Blackheart

Not all Chaos Space Marines fell during the Horus Heresy. Huron Blackheart of the Red Corsairs is a more recent convert. Leader of the loyalist Red Corsairs, he was assigned to patrol the Maelstrom, a much smaller area of warp instability like the Eye of Terror. Lufgt Huron was not overly devoted to the Imperium, however, and, over time, began to stray from official doctrine. Eventually he led the Red Corsairs in rebellion, taking over the planet Badab and making it his own personal kingdom. The Imperium noticed – and, after a vicious war known as the Badab War, Huron Blackheart and the Red Corsairs were ousted. Now they make the Maelstrom their home, sending out raids for supplies, pirating nearby shipping lanes, and always working to further Huron Blackheart’s dreams for power.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community artwork showing Lucius The Eternal

Lucius the Eternal

Once upon a time, Lucius was simply a legionnaire of the Emperor’s Children who was exceptionally devoted to mastering the blade. This desire for perfection is common in many of this legion, but Lucius took it to extremes. After the legion fell to Chaos, he continued his quest, facing down many in single combat to prove that he is the finest swordsman who ever existed. Blessed by Slaanesh, he has unnatural abilities at his beck and call, and, even though he has been slain many times, he always returns, emerging from the skin of the victor like a parasite.

Haarken Worldclaimer, Herald of the Apocalypse

Abaddon the Despoiler cannot be everywhere – so he uses Haarken Worldclaimer as his voice and mouthpiece. If Chaos has a direct human form, it may be in Haarken Worldclaimer, who takes a savage glee in battle, with his vast army of jetpack-borne Chaos Raptors. You’ll often find Haarken sent ahead of the Black Legion, sowing discord wherever he goes, with fast strikes designed to spread fear and disruption. Though he is not a Night Lord, he weaponises fear much as they would, able to drive his foes to madness and worse through manipulation of terrifying messages and broadcasts.

Khârn the Betrayer

Khârn wasn’t always known as the Betrayer. Once, this World Eater was an intelligent and empathetic warrior who only took pleasure in bloodshed once his terrible, torturous brain implants, the Butcher’s Nails, took hold. After many lifetimes fighting in the eternal war, countless losses (including his much beloved friend Argel Tal), and seeing his Primarch, Angron, become a Daemon Prince, Khârn has descended into a rage that will never end. He finally became known as The Betrayer when he, in a frenzy, turned on his own forces, slaughtering scores of them before he could be subdued. Now he is Khorne’s fury incarnate, always where the fighting is thickest, wielding his Primarch’s long-forgotten axe as he hews skulls for the Throne of Skulls and spills blood for the Blood God.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community photo showing chaos space marines fighting imperial guard troopers

Chaos Space Marines in 9th Edition

Chaos Space Marines are one of the most common armies you’ll face in games of Warhammer 40k (after their loyalist brethren, of course). In general, they receive a fair amount of attention both from Games Workshop and from the community, and, as a result, you’ll find some interesting rules and ways to play when you set down a Chaos Space Marine force on the tabletop.

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With so many different legions to choose from, you’ll have a huge array of choices ahead of you; some legions favour Psychic abilities, for instance, whilst others prefer going toe-to-toe in melee. There are, however, some rules that are universal and will affect Chaos Space Marines no matter which legion you plump for, so let’s dive into how Chaos Space Marines perform in the 9th Edition of Warhammer 40,000.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community artwork showing a Dark Apostle model with attendants

Psychic abilities

Kicking off all things Psyker: the Dark Hereticus discipline contains some of 9th Edition’s best spells. In particular you’ll see a lot of mileage out of Death Hex, a power that strips a visible unit within 12” of their invulnerable saves for a turn. If you’re facing off against an army that relies on this in lieu of having tough models, this can be devastating.

Prescience grants a unit +1 to hit all turn

Another brilliant Psychic ability is Prescience, which gives a nice little +1 buff to all hit rolls until your next Psychic Phase. With buffs being a little less buff-y in 9th Edition, this is a reliable way to boost your army’s power.

Lastly, Warptime is an absolute standout ability that lets a unit within 3” of the casting Psyker move again, as if it were the movement phase. See your army race up the board with this one, surprising your enemy by putting even slow-moving units where they least expect.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community artwork showing Forgefiend models


When playing a Chaos Space Marine army, you’ll probably find yourself relying on Stratagems quite heavily, meaning you’ll need to keep an eye on your Command Points. This is because, as with Psychic abilities, Chaos Space Marines have access to some brilliant Stratagems that can make the difference between victory and defeat.

Daemonforge, for example, lets a Daemon Vehicle reroll failed hit and wound rolls for the rest of the phase -great for ensuring a key vehicle gets its damage done.

Endless Cacophony allows a Slaanesh Infantry or Bike unit to shoot again, which, when used correctly, can be devastating. Imagine an Obliterator squad shooting twice in one turn. Horrifying.

Finally, Veterans of the Long War lets an Infantry or Biker unit add +1 to wound rolls until the end of the phase, which just makes taking lives in the name of the dark gods that little bit easier.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community photo showing a Lord Discordant model

Chaos Space Marines in close combat

The other areas where Chaos Space Marines excel is in Melee, as they have some of the finest melee troops in the game, with Berserkers and Possessed ready and very willing to positively rip opponents limb from limb.

Chaos Space Marines also have access to some cheap troops, with recent points re-balancing meaning that you can easily field swathes of useful cannon fodder, in the shape of Cultists. HQs and Characters have also recently seen their usability buffed, with many Chaos Space Marine HQs and Character models offering key versatility on the battlefield (all hail the Lord Discordant).

Daemon summoning

Somewhere in the middle of usability when it comes to a Chaos Space Marine army in 9th Edition is the Daemonic Ritual rule. This rule allows a Character model to attempt to summon daemonic reinforcements from the same Chaos God that they worship.

Like many Chaos rules, Daemon summoning can be very luck based

This might, on the face of it, be a wonderful way to customise your force once the battle has started – as you could theoretically summon in melee or ranged support if you’re desperately in need of them. Unfortunately, summoning, like many Chaos-specific rules, can be a little luck based, as you’ll need to roll for them. This means you might not get the units you wanted if you roll poorly – or could even end up inflicting mortal wounds on your would-be summoning Character.

It also means you need to take a smaller force at the start of the battle, as you’ll need to set aside points to use for your summoned troops. These all make summoning a little less viable, unless you’re playing a legion such as the Word Bearers who have specific rules to offset the downsides.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community photo showing Word Bearers Chaos Terminator models

Two wound Chaos Space Marines when?

Where Chaos Space Marines may need a little extra support in 9th Edition is in their shooting (which remains as unpredictable and short-ranged as it did in 8th Edition) and, significantly, in their durability.

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After the rollout of Space Marines’ beefy, two-wounds-per-model Primaris units, GW announced that all fully-fledged Space Marines (loyalist or traitor) would be bumped up to two wounds with the release of their 9th Edition codexes, but not before.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community artwork showing a khorne berzerker

We now know the remaining codex release dates for 2021, and, sadly, we’ve seen neither hide nor hair of the Chaos Space Marines 9th Edition codex just yet. Consequently, your average Chaos Space Marine is still a chunk weaker than most power-armoured foes, and, as such, must be protected if you want to see them engage with the enemy.

Chaos Space Marines can be quite competitive in the right hands

Overall, Chaos Space Marines are in an in-between spot right now in 9th Edition. Without a 9th Edition codex, they haven’t had the benefit of a large-scale rebalancing or critical look at their rules; in addition, they carry over some of the nagging issues they had in 8th Edition. That said, they can be a competitive army in the right hands, and feature strong units, Characters, and rules that can be brutal when used correctly. If nothing else, Chaos Space Marines in 9th Edition have more options available to them than nearly any other army barring Space Marines, meaning that, if there’s a way you’d like to play them, you can. Their breadth, along with the ability to bring in Chaos Daemons as support, means you can enjoy the best of what Games Workshop has to offer, both in terms of rules and models.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community photo showing a large chaos space marines army fighting Ultramarines

How to start collecting Chaos Space Marines

When approaching a brand new Chaos Space Marine army, there’ll be a variety of ways to build out a competitive, complete force, which will depend on the way you want to go and what you want to focus on. Still, there are a few basics that every Chaos Space Marine army can benefit from, so let’s take a look at them.

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Firstly we’d definitely recommend getting your hands on the revamped Start Collecting! Chaos Space Marines box. This contains a Master of Possession, a Venomcrawler, two Obliterators, two Greater Possessed, and a unit of ten Chaos Space Marines. This is an incredibly versatile box, giving you access to Psychic abilities, a strong vehicle, two of the best shooting models that Chaos Space Marines have access to, two powerful melee models, and a standard workhorse squad of the main guys themselves: the Chaos Space Marines.

Warhammer 40k Chaos Space Marines faction guide Warhammer Community photo showing Khorne berzerker models

From there, you should look at providing yourself a little defence. What’s more defensive than a meat shield? Nothing, so get grabbing some Chaos Cultists. These are a horde unit and won’t do much in either melee or ranged combat, but they will do one thing: they’ll draw fire whilst you get your units into position. Don’t feel sad about seeing them get mown down; they’re only humans.

Possessed have great synergy with the Greater Possessed from your Start Collecting box

As we mentioned above, when it comes to melee, you can’t do better than Berserkers or Possessed. Berserkers make a truly unholy number of attacks with chain axes when they get into close combat, whilst Possessed have great synergy with the Greater Possessed from your Start Collecting! box. Choose either, or both! Indulge yourself; it will please Slaanesh. When it comes to shooting, you’ll already have some Obliterators – which will consistently put the fear of the dark gods into your foe – but, for true versatility, you can’t go wrong with some Havocs. These are your heavy weapon troops, and can come equipped with a wide array of weapons, meaning you’ll have some swiss-army-knife ranged support for your battlefield adventures.

To build out some character in your force, we’d recommend looking at a Sorcerer with Jump Pack, to be able to take advantage of more Psychic abilities while zipping around the board, giving Warptime to your troops in unexpected places, and keeping your opponent on their toes. In addition, a Dark Apostle is an essential purchase, as they give your army access to lots of buffs and effects through their prayers – which can help make your force more competitive.

Our final recommendation for your starter Chaos Space Marine army is a Chaos Rhino. What good is a melee unit if you can’t get it into melee? This transport should see your survivability improve somewhat, especially if you’re using Berserkers – so stuff them on board and race to the front as fast as you can.

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From there on, what you purchase will depend on which legion you’re intending your army to be from. For a Word Bearers army, you may want to focus on daemonic troops, such as more Possessed, or even dipping a toe into actual Chaos Daemons. For Night Lords, you could be looking at some Warp Talons and Raptors to divide up your enemy’s forces with rapid attacks. Or, if you’re looking at making a World Eaters army, you’ll want more Berserkers. A lot more Berserkers. And then even more Berserkers.

Now you should be more acquainted with the fearsome, fun-loving chaps who make up the Chaos Space Marines, with a few ideas of what to watch for on the battlefield, and who you might want to pick up when building a force. Just remember: the Chaos Gods are fickle, but, if you do your best to please them, you’ll soon see your opponent’s army burn in the fires of your unholy vengeance.