Grey Knights: Warhammer 40K Lore Guide

Most citizens of the Imperium will live and die without ever learning that daemons are real. Fewer still will ever hear the name of the warriors who stand between humanity and the Ruinous Powers' most terrible servants. They wear silver armor etched with sacred wards. Every one of them is a psyker. Every one of them has been tested, body and soul, against the corruption of the warp and found incorruptible. They are the Grey Knights, the Chamber Militant of the Ordo Malleus, and they exist for one purpose: to hunt and banish the daemon wherever it appears.

Founded in secret in the dying days of the Horus Heresy, the Grey Knights are the most mysterious Chapter of Space Marines in the Imperium. Their fortress lies on Titan, a moon of Saturn, and the location is one of the Imperium's best-kept secrets. This guide explores their origins, their unique recruitment and training, their Brotherhoods and heroes, their place in the Inquisition, their wars against the daemonic legions and how they play on the tabletop. For a look at every other army in the setting, see our Warhammer 40K factions guide.

If you are a newcomer to Warhammer 40,000, the Grey Knights are a fascinating gateway into the setting's darkest secret: the warp, and the creatures that dwell within it. They are knights in a literal sense, sworn to a holy quest that can never truly end.

Grey Knights at a Glance

Origins: Malcador's Secret Order

As the Horus Heresy tore the Imperium apart, the Emperor and His regent, Malcador the Sigillite, faced a terrifying realization. The traitor Legions were not merely rebels; they had become the servants of the Chaos Gods, and the daemons of the warp were spilling into reality alongside them. The Imperium needed a force that could face these entities without falling to them, and that force could not be built from Legions whose loyalty had already been tested and broken.

Malcador gathered a small band of warriors drawn from both loyalist and traitor Legions, the so-called Knights Errant, who had proven their loyalty under the most extreme circumstances. Some of these figures appear prominently in Black Library's Horus Heresy novels. According to the lore, these warriors played a part in the birth of the new order, which was founded in secret on Titan as the Heresy drew to its close. The details of the Grey Knights' gene-seed remain a mystery that the lore keeps deliberately ambiguous; it is said to be unique to the Chapter, and is sometimes rumored to have come from the Emperor Himself.

From the beginning, the order was surrounded by secrecy. It answered to no Primarch and kept no records outside its fortress. When the Inquisition was established in the aftermath of the Heresy, the Grey Knights became the Chamber Militant of its Ordo Malleus, the branch dedicated to daemonic threats, and the two have been intertwined ever since.

Recruitment and Training: Forging the Incorruptible

Every Grey Knight is a psyker. Recruits are taken from across the Imperium, often from among those identified by the Inquisition or the Black Ships as possessing psychic potential. Only those with exceptional mental resilience, purity of will and freedom from taint are considered. The training on Titan is brutally demanding. Recruits endure physical and psychic trials, sustained exposure to horrors, and an education in the rituals and lore of daemon-hunting. Many do not survive, and those who fail are never allowed to leave carrying the Chapter's secrets.

Those who do emerge are among the most formidable warriors in the galaxy. A Grey Knight's psychic gifts are shaped to work in concert with his brothers, so that a squad can weave their powers together into a single, devastating force. Their armor and weapons are blessed, warded and inscribed with sacred texts. Their minds are trained to resist possession and temptation. The Chapter's lore proudly claims that no Grey Knight has ever fallen to Chaos, though in a setting as grim as this one, many readers suspect the truth is simply better hidden.

The Brotherhoods, the Purifiers and the Paladins

The Grey Knights do not follow the Codex Astartes. Instead, the Chapter is divided into eight Brotherhoods, each led by a Grand Master. Above them stands the Supreme Grand Master, who commands the entire Chapter. Each Brotherhood includes Brother-Captains, Brotherhood Champions, Librarians, Chaplains and Techmarines, along with a mix of power-armored squads and Terminators.

The Order of Purifiers

Within the Chapter exists an even more elite inner order: the Purifiers. These are battle-brothers judged to have souls of exceptional purity, who wield the sacred cleansing flame and serve as the Chapter's last line of defense against internal corruption. They are led by Castellan Garran Crowe, who guards the cursed blade Antwyr, a daemon-bound weapon so dangerous that only a soul as pure as his can hold it without being corrupted.

The Paladins

The Paladins are the Chapter's champions, veteran Terminators who have completed a series of grueling trials and earned their place among the Chapter's champions. They are among the deadliest close-combat warriors in the galaxy and are often deployed against the mightiest daemons.

Heroes of Titan

• Kaldor Draigo: the Supreme Grand Master of the Grey Knights. After a climactic battle against a powerful daemon, he was trapped in the warp and has been wandering the Realm of Chaos ever since, fighting the Chaos Gods on their own ground. Among his legendary deeds, he carved his name into the heart of the Daemon Primarch Mortarion. Draigo's wanderings remain one of the most debated pieces of 40K lore.
• Castellan Garran Crowe: the leader of the Purifiers and the bearer of Antwyr, the cursed blade.
• Grand Master Voldus: the Grand Master of the Third Brotherhood and one of the most powerful psykers in the Chapter.
• Brother-Captain Arvann Stern: a hero locked in a long-running feud with a daemon called M'kachen, which has hunted him across many battlefields.

The Grey Knights and the Inquisition

As the Chamber Militant of the Ordo Malleus, the Grey Knights are the direct military arm of the Inquisition's daemon hunters. A Malleus Inquisitor can call upon them for aid, and the Grey Knights in turn may act as investigators and judges themselves. Their relationship with the Inquisition and its agents is close but not always comfortable. The Grey Knights consider themselves answerable to the Emperor's will above any individual Inquisitor, and in rare cases they have turned their blades on Inquisitors who strayed into heresy.

Their partnership with the Ordo Malleus is mirrored in the other two great Ordos. The Deathwatch serves as the Chamber Militant of the Ordo Xenos, hunting alien threats, while the Adepta Sororitas serve the Ordo Hereticus. Together, these three forces form the specialized military tools the Inquisition uses against the Imperium's most dangerous foes.

Secrecy and Its Price

The existence of daemons is one of the Imperium's most dangerous secrets. If the masses learned that the warp was home to entities that feed on human emotion and that the Chaos Gods could whisper into any mind, the result could be panic, heresy and further corruption. For this reason, the Grey Knights and the Ordo Malleus go to extreme lengths to suppress knowledge of daemonic incursions.

This has led to some of the darkest episodes in Imperial history. The most famous is the First War for Armageddon, in which the Grey Knights fought the Daemon Primarch Angron of the World Eaters and banished him back to the warp. In the aftermath, the Inquisition ordered that the surviving witnesses, including Imperial Guardsmen who had fought beside them, be purged or mind-wiped to protect the secret. The Space Wolves, who had also fought on Armageddon, refused to allow it, and the resulting confrontation began a long-running feud between the Wolves and the Inquisition.

Such episodes reveal the Grey Knights' tragedy. Their absolute devotion to their cause makes them heroes and monsters at once: they will save a world from the daemon and then scour its surviving population to keep the secret.

Wargear and War Machines

Grey Knights wear Aegis power armor, which is inscribed with hexagrammic wards and psychic circuitry that protect against the warp's influence. Their signature weapons are Nemesis force weapons, which channel the wielder's psychic energy into a blade, halberd, falchion or staff that can wound daemonic essence. Most battle-brothers also carry wrist-mounted storm bolters, firing blessed rounds.

The Chapter's specialized units reflect their way of war. Strike Squads are the core of the Chapter, teleporting into battle alongside Terminators. Interceptor Squads use personal teleporters to dart across the battlefield. Purgation Squads bring heavy weaponry such as psycannons and incinerators. The Nemesis Dreadknight is a hulking exoskeleton piloted by a Grey Knight, large enough to grapple with Greater Daemons. The Chapter also uses Land Raiders, Stormravens and Dreadnoughts, many of them inscribed with sacred texts.

The Grey Knights in the Indomitus Era

The opening of the Great Rift was a catastrophe for the Grey Knights. Daemonic incursions erupted across the galaxy in numbers never before seen, and the Chapter was stretched thinner than ever. With Kaldor Draigo still lost in the Realm of Chaos, the Brotherhoods fought under their own Grand Masters on countless worlds, rarely able to rest or regroup.

The secrecy that once defined the Chapter is also harder to maintain. With daemons now openly assailing entire sectors, the Grey Knights increasingly fight alongside Space Marines, the Astra Militarum and the Adeptus Custodes, whose golden warriors share their absolute dedication to the Emperor. Their foes include the full range of the Chaos Daemons, from the legions of the four Chaos Gods to the countless lesser horrors of the warp.

In this era, the Grey Knights are both more necessary and more burdened than ever before. Every daemon they banish returns to the warp to be reborn, while every brother they lose is nearly impossible to replace.

How the Grey Knights Play on the Tabletop

On the tabletop, the Grey Knights are an elite Space Marine army built around three pillars: mobility, psychic power and melee. Almost every unit can teleport onto the battlefield, letting you strike where your opponent is weakest and redeploy across the board. Psychic abilities support and enhance this aggression, while power-armored and Terminator squads excel at cutting through enemy lines with Nemesis weapons.

Because every model is a psyker and a veteran warrior, the army fields very few models. That makes it fast to paint but unforgiving on the table: every unit counts, and losing a key squad hurts. Grey Knights reward players who enjoy surgical strikes, careful positioning and a striking silver-and-red aesthetic, and they make a natural opponent for daemon-heavy armies.

Grey Knights FAQ

Are the Grey Knights Space Marines?

Yes. The Grey Knights are a Space Marine Chapter, though a highly unusual one. Every battle-brother is a psyker, they follow their own organization instead of the Codex Astartes, and they serve as the Chamber Militant of the Inquisition's Ordo Malleus. They share the transhuman biology of the Space Marines but have a mysterious gene-seed of their own.

Why are they called the Grey Knights?

The name comes from their unpainted, silver-grey armor and their knightly role as holy warriors sworn to a sacred quest. Within the lore, the name is also tied to their secrecy: they are a shadowy order, unknown to most of the Imperium.

Has a Grey Knight ever fallen to Chaos?

According to the Chapter's own claims, no Grey Knight has ever fallen to Chaos. The recruitment, training and spiritual discipline of the Chapter are designed to make this impossible. Whether that is literally true or simply the official record is left ambiguous, which adds to the order's mystique.

Where is the Grey Knights' homeworld?

The Grey Knights' fortress-monastery is on Titan, a moon of Saturn in the Sol System. The Citadel of Titan houses their armories, libraries and vaults, including many daemonic artifacts too dangerous to destroy.

Who is Kaldor Draigo?

Kaldor Draigo is the Supreme Grand Master of the Grey Knights. He has been lost in the Realm of Chaos for centuries, wandering the domains of the Dark Gods and fighting daemons in their own territory. His legend includes carving his name into Mortarion's heart, a feat that remains one of the most famous and debated episodes in 40K lore.

What is the difference between the Grey Knights and the Deathwatch?

Both serve the Inquisition, but they face different threats. The Grey Knights are the Chamber Militant of the Ordo Malleus and fight daemons, while the Deathwatch are the Chamber Militant of the Ordo Xenos and fight aliens. The Grey Knights are a single Chapter of psykers, whereas the Deathwatch draws veterans seconded from many different Chapters.

Continue Exploring

• Warhammer 40K Factions: Complete Guide to All 29 Armies — every army, its lore and how it plays
• The Chaos Daemons — the warp-born legions the Grey Knights exist to banish.
• The Deathwatch — the Inquisition's alien-hunting Chamber Militant.
• The Adeptus Custodes — the golden guardians of the Emperor's Throne.
• The Imperial Agents — the Inquisition and the Officio Assassinorum.

Name your own battle-brothers with the Space Marine name generator, or browse every guide in the Warhammer 40K lore hub. To chronicle your own Brotherhood's war against the warp, Anima is free and runs in your browser with no account: a wiki, a timeline, and campaigns with a live DM screen.