The setting

The Imperium of Man

A vast, oppressive, decaying theocracy of a million worlds ruled in the name of the undying God-Emperor.

Humanity's galaxy-spanning empire is a grimdark theocracy that venerates the half-dead Emperor interred on the Golden Throne. It fights with the sheer mass of the Astra Militarum, the transhuman Space Marines, the tech-worshipping Adeptus Mechanicus and the zealous Adepta Sororitas. Its defining tragedy is that the Emperor preached atheism yet became a god, and the Imperium stagnates, hoarding lost technology it no longer understands. In the Era Indomitus the resurrected Primarch Guilliman leads a desperate crusade to hold an Imperium fighting on every front.

Notable: The Emperor, Roboute Guilliman, Lion El'Jonson, Marneus Calgar, Commander Dante, Saint Celestine

The Forces of Chaos

Corrupted traitors, daemons and the four Ruinous Powers waging an eternal Long War against the Imperium.

Chaos comprises the daemonic legions of the four Dark Gods and the mortal followers who serve them, chief among them the traitor Space Marine Legions who fell during the Horus Heresy. Sheltered in the time-warped Eye of Terror, Heresy-era champions like Abaddon and the Daemon Primarchs endure into M41 to launch periodic Black Crusades. They are driven by raw emotion made manifest — Khorne's rage, Nurgle's despair, Tzeentch's ambition, Slaanesh's excess.

Notable: Abaddon the Despoiler, Magnus the Red, Mortarion, Angron, Fulgrim, Ahriman, Be'lakor

Aeldari (Eldar)

A dying, ancient elder race of psychics whose decadence birthed Slaanesh and doomed them to be hunted at death.

The Aeldari once ruled the galaxy but their hubris created Slaanesh, whose birth devoured most of their species. The survivors are scattered into the ascetic Craftworld Asuryani of the Path System, the fringe Exodites and the warrior-poet Harlequins of Cegorach. Their souls burn so brightly that Slaanesh devours any unprotected Aeldari at death, so they use soulstones interred in their Craftworlds' Infinity Circuits. They fight with refined, fragile precision, awaiting the awakening of their death-god Ynnead.

Notable: Eldrad Ulthran, Yvraine

Necrons

An ancient race of soulless undying robots awakening from sixty million years of slumber to reclaim the galaxy.

Once the fragile, death-obsessed Necrontyr, the Necrons traded their flesh and souls for immortal living-metal bodies in the biotransference that fed the C'tan. They slept for sixty million years and now wake unevenly to rebuild their dynastic empire. Only the highest nobility retain real personality. Under the returned Silent King they pursue the Pariah Nexus, vast null-fields meant to nullify psychic powers and disrupt the Tyranid Hive Mind.

Notable: Szarekh the Silent King, Imotekh the Stormlord, Trazyn the Infinite

Orks

A brutal, comical, ever-expanding fungal warrior race that lives only to fight — and grows stronger the more it does.

Descended from the Old Ones' Krork shock-troops, the Orks are a green-skinned species engineered for war who reproduce via spores and worship the twin gods Gork and Mork. They live for the joy of battle, gathering into ever-larger WAAAGH! that gain self-fulfilling psychic momentum. Their jury-rigged tech works largely because they collectively believe it will. Under Ghazghkull Thraka they have launched the prophesied Great WAAAGH!

Notable: Ghazghkull Thraka

Tyranids

An extragalactic swarm, the Great Devourer, that consumes all biomass and reprocesses it into more living weapons.

The Tyranids strip entire worlds of all life, reprocessing the biomass into living ships and warriors. Every creature is coordinated by the gestalt Hive Mind and preceded by the Shadow in the Warp, which drowns astropathic communication and isolates systems before they are devoured. Major Hive Fleets like Behemoth, Kraken and the colossal Leviathan attack relentlessly from beyond the galactic plane. They are a mindless, unstoppable tide of pure hunger.

T'au Empire

A young, idealistic, technologically advanced xenos civilization expanding under the philosophy of the Greater Good.

The T'au are a comparatively young species united under the Tau'va — the Greater Good — which subordinates the individual to collective progress. Divided into castes, their armies favour advanced ranged firepower, battlesuits, drones and mobile high-tech warfare over close combat. They expand through Sphere Expansions blending conquest with diplomacy; Commander Shadowsun's Fifth Sphere renewed their growth.

Notable: Commander Shadowsun

Drukhari (Dark Eldar)

Sadistic Aeldari raiders of the hidden city Commorragh who must torture others to stave off the death of their souls.

The Drukhari are the unrepentant heirs of the Aeldari pleasure cults, surviving the Fall hidden within the Webway city of Commorragh. Slaanesh leeches their souls while they still live, so they raid realspace to harvest the pain and souls of captives — a craving called the Thirst. They are lightning-fast piratical raiders who strike from the Webway and vanish, the dark mirror of their ascetic Craftworld kin.