There has been little active curation of Warhammer 40K canon.
Instead,
Games Workshop and its publishing arm Black Library has taken the
stance that everything ever written about its sprawling lore is “true” — all
of it is canon, more or less since its inception in the 1980s. Just like
actual history, no single narrator or historian in the grim darkness of the
far future is 100% reliable. Instead, it’s up to the reader to sift through all
the dusty — and highly collectible — tomes in order to parse its primary
sources.
Much like real history, it can be hard to piece everything together. Fan
wikis and forums can be esoteric and packed with proper nouns.
Meanwhile, since the narrative has never been rebooted or retconned,
there are few official on-ramps for new players. But it’s possible to
engage with the 40K fandom with a running start, gathering up bits of its
nearly 40-year backstory as you go along. We’ve created this guide with
newcomers in mind, and we’ll pepper our primer with recommendations
for games, books, videos, and even entire factions that you might want to
learn more about.
WARHAMMER 40K’S SETTING
mage: Games Workshop
            Warhammer 40K began as a pastiche of science fiction and fantasy
            tropes. For instance, looking back at its inception in the late ’80s, you’ll
            find elements from Frank Herbert’s Dune, with a God-Emperor, a hatred
            of AI, and the spacefaring Navigators. But, even early on, you’ll also find
            more literary call-backs, including nods to John Milton’s Paradise Lost.
            Its earliest official work, Warhammer 40,000: Rogue Trader (written by
            Rick Priestly), begins with a preamble, a kind of Star Wars-style opening
            crawl that lays out the most basic facts that the reader needs to know. It’s
            been changed and altered over the years, but here are the original words
            from 1987:
            For more than a hundred centuries the Emperor has sat immobile on the Golden Throne of Earth. He is
            the Master of Mankind by the will of the gods and master of a million worlds by the might of his
            inexhaustible armies. He is a rotting carcass writing invisibly with power from the Dark Age of
            Technology. He is the Carrion Lord of the Imperium to whom a thousand souls are sacrificed every day,
            and for whom blood is drunk and flesh eaten. Human blood and human flesh — the stuff of which the
            Imperium is made.
            To be a man in such times is to be one amongst untold billions. It is to live in the cruelest and most bloody
            regime imaginable. This is the tale of these times. It is a universe you can live in today if you dare — for
            this is a dark and terrible era where you will find little comfort of hope. If you want to take part in the
            adventure then prepare yourself now. Forget the power of technology, science and common humanity.
            Forget the promise of progress and understanding, for there is no peace amongst the stars, only an
            eternity of carnage and slaughter and the laughter of thirsting gods.
            But the universe is a big place and, whatever happens, you will not be missed...
            Later rewrites of this piece add in references to the top-selling Space
            Marines and their comrades, but the bleakness of the God Emperor’s
            reign has never been in question.
                  Warhammer 40K was originally conceived as a political satire and as an anti-fascist work
                  fiction. Nevertheless, over the decades, the hobby has attracted no small number of right-
                  fans who buy into either the in-universe propaganda of the Imperium, or the marketing
    materials that describe the Space Marines and friends as noble protectors of humanity. In
    recent years, Games Workshop has spoken out against this fan movement, itself calling b
    the original preamble penned by Priestly.
MEET THE IMPERIUM OF MAN
Before we delve into the finer details of the modern setting, it’s clear that
humanity should not be thought of as the good guys in 40K. From the
very beginning of the franchise to the current day, the Imperium is one
of the most villainous factions in the entire galaxy, as cruel or perhaps
more cruel to its own citizens than it is to outsiders it considers to be a
threat to its way of life.
The Imperium remain the franchise’s nominal main characters. They
give the larger fiction its point-of-view in most instances, and absorb
much of the spotlight. This is even more extreme with the Space
Marines, Games Workshop’s top sellers. Authors will often hype them up
and praise their virtues, outright ignoring or otherwise skipping over
uncomfortable topics like their tendency toward fascism and their
origins as brainwashed child soldiers.
    THE IMPERIUM FUCKING SUCKS TO LIVE IN, BUT
    IT’S FUN TO READ ABOUT, AND THEY HAVE ONE
    REDEEMING QUALITY — THEY AREN’T THE OTH
    GUYS
So, why are they so dang fun to read about? Take Frank Herbert’s Dune,
gothic Christian imagery ramped up to 11, and giant war machines.
Throw them all in a blender, and you get 40K’s Imperium of Man. Battle
nuns drop cathedral tanks from orbit on their enemies. The Adeptus
Mechanicus, a transhuman faction of religious cyborgs, chant religious
rites to the machine spirits inside tanks. The Astra Militarum, also
known as the Imperial Guard, is a faction made up of trillions of normal
dudes in flak armor whose commissars urge them forward at gunpoint.
It’s a wild take on dystopian, far-future sci-fi, far removed from any of
our current problems. The Imperium fucking sucks to live in, but it’s fun
to read about, and they have one redeeming quality — they aren’t the
other guys.
RECOMMENDED MEDIA:
Space Marine is a solid and accessible action game that stars Captain
Titus, an Ultramarine at war against the Orks invading Forge World
Graia.
Darktide is the best chance you’ll have to explore a Hive City for yourself.
The level design and soundtrack are immaculate and make Warhammer
40K feel very tangible.
The Vaults of Terra series by Chris Wraight is a procedural crime drama
that takes place on Terra, at the foot of the Golden Throne itself.
The Inquisition novels by Dan Abnett make up a sprawling trilogy of
trilogies, packed full of day-to-day life for the poor souls in the Imperium
— and the Inquisitors who watch over them.
Fire Caste by Peter Fehervari is an Apocalypse Now homage, told
through the tale of Imperial Guard soldiers pursuing warriors of the T’au
Empire.
FROM 15K TO 40K
mage: Games Workshop
            The Imperium is based on real-world history, but since it’s so far in the
            future, there are some big gaps in the timeline. We know that the
            Emperor of Mankind and his closest group of allies are Perpetuals,
            immortal humans that are reborn into new vessels after perishing.
            They’ve been in the background of all of history, pulling strings and
            setting up pieces on the chess board. Here are some of humanity’s
            historical eras that end up setting the scene for 40K.
            Dark Age of Technology (~15,000-25,000 CE): Long after we were
            all gone, humanity hit its pinnacle and created a fully automated space
            utopia. Then, the AI-controlled Men of Iron rose up to kill humanity —
            and almost succeeded. This is why AI has been outlawed in 40K; the
            acronym now stands for abominable intelligence. In its place is a kind of
            horrific bio-engineering, which uses human minds and bodies as the
            material for new robot-like entities like servo-skulls and servitors. The
            Dark Age tech that survived usually crops up again and again in the
            modern timeline to cause some kind of problem, but we otherwise know
            very little about this era.
Age of Strife/The Long Night: With space travel shut off and the
Men of Iron revolt leaving humanity in ruins, the survivors fell to civil
war, Mad Max: Fury Road style, but across multiple star systems. The
Emperor of Mankind showed up on the main stage, created a faulty race
of transhuman soldiers known as the Thunder Warriors, and forcibly
united humanity under his banner. Large parts of the race were stranded
because their faster-than-light tech went down with the Dark Age of
Technology, and they were left to face constant assault and enslavement
from alien xenos.
The Great Crusade: The Emperor used his gang of genetic scientists to
improve upon the Thunder Warriors, who were all dying horribly. The
first step was to create 20 perfect sons based on the Emperor’s own DNA,
but Chaos interfered by taking these Primarch and yeeting them to the
far corners of the galaxy. The Imperium of Man began to scour the stars,
searching for the Primarchs even as it began bringing all human worlds
back into the fold – whether they wanted to join or not. During this time,
two Primarchs were disappeared by the Imperium for unknown reasons,
and permanently scrubbed from the historical record.
mage: Games Workshop
            Horus Heresy: The Horus Heresy is the civil war that followed the
            Great Crusade. For those living in the current timeline of 40K, the
            Heresy — and even the Primarchs themselves — are the stuff of myth and
            legend, only known through the practices of Imperial cults and scraps of
            history passed down through the generations. Their story, set in the year
            30K, has become so popular that it’s now its own standalone wargame
            accompanied by over 60 novels. This is a big Greek tragedy, where half of
            the Primarchs fall to Chaos and rebel against their tyrannical father. In
            the end, Horus is obliterated and the Emperor is badly wounded, leading
            to the slow decay of the Imperium and the institutionalization of a
            mandatory religion worshiping the God-Emperor. Ironic, considering the
            guy was a mega atheist, but he’s too busy sitting on the Golden Throne —
            an ancient bit of tech that just barely manages to keep him alive — to
            have any say about it.
            Warhammer 40,000: This is the era that most fans of 40K, lapsed or
            otherwise, think of when they think of the franchise. But, for real-world
            decades, the “main plot” of the universe sat stagnant; there were no
            further progressions in the main setting, just new editions of the game
            that were pumped out on a roughly three-year cycle. Instead, the Black
            Library and publishing arms of Games Workshop fleshed out what life
            was like in the Imperium of Man with works like Dan Abnett’s
            Inquisition novels, or Sandy Mitchell’s Ciaphas Cain novels.
            Smaller-scale stories unfolded in this setting, but there were no major
            shake-ups until recent years.
            Era Indomitus (42,000 CE): In the Gathering Storm campaign
            supplement books released in 2017, one loyalist Primarch — Ultramarine
            and administrator extraordinaire, Roboute Guilliman — returned.
            Unfortunately, around the same time, Chaos also split the galaxy in half,
            creating the Cicatrix Maledictum. Warhammer 40K and its extended
            materials have focused on the response to Guilliman’s return and the
            new nature of the post-split galaxy. A second loyalist Primarch, Lion
            el’Jonson, has recently returned as well, setting up a post-Heresy grudge
            match for the very future of the Imperium itself.
            THE ULTIMATE ANTAGONIST: CHAOS
mage: Games Workshop
            The Imperium sucks, but it’s so awful for a reason — and that reason is
            Chaos, the ever-present enemy that feeds off humanity and would love
            nothing more than to keep them as slaves and soul cattle.
            Chaos is powered by the Warp, a roiling mirror realm of emotion that
            exists parallel to realspace. The Warp is a corrupting force; while
            Imperial Psykers and Space Marine Librarians use the stuff to fight off
            the enemies of mankind, they’re continually at risk of corruption — or of
            accidentally summoning a demon. You can’t escape these malevolent
            energies, especially after the Cicatrix Maledictum was torn across the
            galaxy and the Warp began continually spilling out of it.
    CHAOS IS POWERED BY THE WARP, A ROILING
    MIRROR REALM OF EMOTION THAT EXISTS
    PARALLEL TO REALSPACE
There are four main Chaos Gods, although recent campaign books like
the Arks of Omen have focused on some mini-Gods and greater daemons
who want to earn a promotion. Each God corresponds to some kind of
powerful emotion.
Khorne is a god of warfare and brutality; his motto is “Blood for the
blood god, skulls for the skull throne.” Tzeentch is the god of change, and
is a patron to sorcerers and schemers around the galaxy. Nurgle is a god
of life, disease, and decay, spreading plagues around the galaxy. Slaanesh
is a god of excess and pleasure, born out of the heights of Aeldari
hedonism. Patrons of Chaos can follow one god, or all four if they feel
like they just can’t commit.
The natural minions of the Chaos Gods are daemons, also known as the
Neverborn. These are creatures from the Warp that can only materialize
in realspace when specific conditions — like copious amounts of human
sacrifice — are met. Cultists and double agents around the galaxy work
on behalf of the Neverborn to make their manifestation possible. The
Gods and their followers continually compete in the Great Game, and
they’re all as likely to backstab each other as actually fight a foe together.
But there are no soldiers of Chaos as ardent or committed as the Chaos
Space Marines who fell in the Horus Heresy. Horribly mutated, forced to
eke out an existence in the Eye of Terror, and constantly struggling with
what remains of their morality and humanity, the Chaos Space Marines
are a tragic mirror of their brothers.
RECOMMENDED MEDIA:
The Night Lords Omnibus by Aaron Dembski-Bowden takes on the
impossible task of turning a pack of Chaos Space Marines into likable
heroes — and pulls it off, with a side order of tragedy.
The First Heretic is another novel by Dembski-Bowden from the Horus
Heresy series, exploring the origin of the Chaos Space Marines — and
why they’re not entirely to blame.
Sabbat War, The Tomb of Vichres, a short story by Justin D. Hill, is a
harrowing account of what it’s like to be a Chaos footsoldier.
XENOS, THE ALIENS NEXT DOOR
The various alien races of the 40K galaxy are not a united front; the only
thing they have in common is that they are not humanity. Each of them
poses a threat to the Imperium of Man in own way, but they are all as
likely to fight each other as roll up on Imperial forces. Many of the xenos
race are tied to the War in Heaven, a truly ancient conflict between the
Old Ones and the C’tan that played out over 65 million years ago. The
Old Ones and C’tan used many of our current xenos races as proxy
forces.
AELDARI
mage: Relic Entertainment
               The Aeldari (formerly known as Eldar) are space elves, and they share
               many of the same traits as their cousins in other fantasy media. They’re
               an aloof species, masters of sorcery and one-time rulers of the galaxy.
               They have access to the Webway, a system of extra-dimensional tunnels
               that allow faster-than-light travel without exposing oneself to the Warp.
               Despite all these sick benefits, their race is now defined by their
               explosive fall to hedonism and hubris. The Aeldari became so decadent
               and arrogant that they murderfucked the Chaos God Slaanesh into
               existence. Oops! Most of the Aeldari pantheon was killed, shattered, or
               kidnapped to the realms of Chaos, with one notable exception.
               The survivors of the Fall have splintered, choosing different ways to
               survive. The Asuryani use Craftworlds, former travel ships the size of
               planets that have been retrofitted to become their primary habitat. The
               Drukhari torture, maim, and wreak havoc on innocents, escaping
               Slaanesh by constantly revitalizing themselves, Elizabeth Bathory-style.
               The Harlequins are warriors who double as performers and artists,
               protected by Cegorach, the Laughing God. There are also the Exodites —
               relatively rural Aeldari who live on Craftworlds and ride dinosaurs — and
the Ynnari, a new faction with recruits from all other Aeldari who pursue
the birth of a new God of Death.
RECOMMENDED MEDIA:
Path of the Eldar is an omnibus that dives into Craftworld society from a
variety of perspectives, giving a solid idea of the cultures and daily lives
of these strange aliens.
Path of the Dark Eldar is the same thing — except it digs into
Commoragh and the sinister machinations of the Drukhari.
Warhammer TV’s Hammer & Bolter series, In The Garden of Ghosts
(subscription only), is a moving story about Aeldari magic and the ties
that bind us to our families.
ORKS
The original satire and humor of 40K still exists, and the Orks are the
best example of it. These guys worship gods named Gork and Mork, love
to fight, and leave spores behind that multiply and grow into more Orks.
The Orks were originally Krorks, engineered by the Old Ones in their war
against the C’tan. Over the millennia, they’ve devolved into giant green
footie hooligans. While other armies boast terrifying technology or
carefully honed weaponry, the Orks will strap a bunch of rockets to an
asteroid and ride it hooting and hollering into a spaceship like a bunch of
big green Dr. Strangeloves. Backed up by an army of little grot minions
and pumpkin-shaped beasts called squigs, they’re always having a blast
in a galaxy of only war — it’s everyone else who finds them terrifying and
lethal.
RECOMMENDED MEDIA:
Shootas, Blood, and Teef is a whimsical run-and-gun game where you
play as one part of a mighty Ork WAAAGH!, destroying everything in
your path.
            Brutal Kunnin’ by Mike Brooks is a surprisingly funny tale of Orks pitted
            against tech priests.
            Ghazghkull Thraka: Prophet of the Waaagh! by Nate Crowley shines a
            light on the Orks’ biggest star, via a tale spun by one of his
            banner-holders to the Inquisition itself.
            Warhammer TV’s Hammer & Bolter series, Old Bale Eye (subscription
            only), is a tall tale told from the Ork perspective.
            TYRANIDS
mage: Games Workshop
            It’s about time we talked about the Tyranids, because these hungry boys
            put the Zerg to shame. The Tyranids are a force from outside the galaxy
            who will serve as the main antagonists of Warhammer 40K’s 10th
            edition boxed set and the upcoming Space Marine 2. They are a highly
            adaptive biological force who devour planets and populations and turn
            them into fuel for more Tyranids. Tyranids are backed up by Genestealer
            Cults, nefarious organizations that infiltrate human societies with the
            eventual goal of overthrowing local resistance and lighting a beacon for
            the Hive Fleets to come and nom on the planet.
            RECOMMENDED MEDIA:
            The Devastation of Baal by Guy Haley is the epic battle of Hive Fleet
            Leviathan and its very earnest effort to absolutely destroy the Blood
            Angels chapter of Space Marines on their home world of Baal.
            Day of Ascension by Adrian Tchaikovsky is all about the Genestealer
            Cults and their sneaky plans to spread the good word of a bug’s life.
            Warhammer TV’s Hammer & Bolter series, A New Life (subscription
            only), will help in your understanding of how Tyranids attack from
            without and within.
            NECRON
mage: Games Workshop
            Once written as terrifying space Terminators (Arnold-style, not Space
            Marine-style), recent revisions to the canon have given the Necron much
            more depth. An ancient race cursed to suffer under a radioactive sun, the
            Necrontyr made a deal with the devil for an end to their suffering. The
            C’tan used biotransference to remove mortality and flesh from the
            Necrontyr, transforming them into the Necrons. While they eventually
            settled down for a long slumber, the Necron are waking up to reclaim the
            galaxy — all while they struggle with immortality and the curse of
            biotransference.
            RECOMMENDED MEDIA:
            The Infinite and the Divine by Robert Rath is one of the best 40K novels
            period, and does wonders to flesh out its Necron stars — you know,
            despite all the metal.
            The Twice Dead King by Nate Crowley shines a light on the enigmatic
            Silent King’s court, telling a tale of Necron nobility and their ambitions.
            The Templin Institute does a great job presenting an in-fiction lore dump
            on the Necron that won’t put you to sleep.
            T’AU EMPIRE
mage: Games Workshop
The T’au Empire are the newest kids on the block, only rising as a
galactic civilization within the last five thousand years. These
blue-skinned, mecha-loving aliens believe in a concept called the Greater
Good. The T’au are divided into four castes — water, fire, earth, and air,
and ruled over by a group called the Ethereals. The T’au will extend the
hand of friendship and explain the value of the Greater Good to potential
new worlds. Those who decline will likely be encouraged to reconsider,
through either diplomacy and soft power, or more direct military action.
The Empire is small, and expands much slower than their competitors —
but they’re also a much better place to live than the Imperium, and
they’ve built a coalition of other alien races who fight under their banner.
RECOMMENDED MEDIA:
Voice of Experience by JC Stearns stars a human member of the T’au,
swayed by the Greater Good. This human perspective gives us new
insight on the Empire.
Broken Sword by Guy Haley is one story from a larger omnibus detailing
a battle between T’au and Space Marines.
LEAGUES OF VOTANN
The Leagues of Votann are space dwarves, previously known as Squats,
who were part of the original setting when it launched in the 1980s.
Previously, it had been claimed that the Tyranids had devoured the
Squats, but Games Workshop recently reintroduced them as the Leagues
of Votann. Turns out they’ve been hiding in plain sight all along,
including on one of the galaxy’s most populous systems, Necromunda.
The Leagues are a highly skilled group on par with the Imperium and the
T’au technologically, but far more insular and nomadic, depending on
the sect. The Votann were once human, and they left the Sol system in
the Dark Age of Technology. After countless generations of genetic
manipulation, distance from humanity, and good old-fashioned
evolution, they’ve become their own species entirely – one that deeply
distrusts the Imperium. They even live alongside Ironkin, who seem
suspiciously similar to the Men of Iron who nearly killed humanity
during the Dark Age of Technology. The Votann get along just fine with
the Ironkin, presumably due to their relatively open minds.
The Leagues of Votann worship Ancestor Cores, enormous
supercomputers that eclipse anything the Imperium has to offer. These
Ancestor Cores are slowly breaking down, like a computer with too many
Chrome tabs, and they are increasingly unreliable as guides. This,
combined with the Cicatrix Maledictum, means the Leagues must once
again venture out into the galaxy.