In Ancient Rome, imperium was the degree of authority vested in a curule magistrate or promagistrate. It meant that a man literally owned the authority of his office, and could not be overruled provided he was acting within the limits of his level of imperium and within the laws which governed his conduct.

Imperium was conferred by a lex curiata, and lasted for only one year. Extensions for a prorogued governor had to be ratified by the Senate and/or the People. Lictors shouldering fasces indicated a man's imperium; the more lictors a man had, the higher his imperium.

A Million Worlds, Unnumbered Souls


The Imperium of Man is the largest empire in the Warhammer 40K universe. For 10,000 years the Imperium has watched over countless galaxies and star systems, with a population running into thousands of billions, and always growing. It is lead by the crippled Emperor of man, once a majestic and powerful figure now bound to the golden throne, mortally wounded. This god-like figure is worshipped throughout the empire, despite his inability to physically do anything. He is the metaphorical essence of hope that man holds onto, has been holding onto and forever will, whatever happens. Without the Emperor, that hope would disappear and the Imperium would destroy itself from inside.

The number of planets and galaxies that have been swallowed by the Imperium is mind-boggling. New systems and planets are always being discovered, being turned towards the emperor's will. At the centre of it all is Terra (i.e. Earth), the most heavily guarded and manned planet in the entire universe. Defences lie light-years away from the planet, protecting the immortal Emperor and his people from certain death. No one has ever managed to get through these defensive measures since the Horus Heresy eleven thousand years ago.

Some systems under the Imperium's rule, however, think of the Emperor simply as a legend or myth, as a long gone hero vanquished centuries ago. To some, he is an omnipresent supernatural force praised daily from the alter much like the real world's Christianity and the worship of God. However, the difference is that the Emperor is very much real and continues to give hope.

However, this great majestic time isn't without strife and conflict. The Imperium is constantly at war, on countless worlds and throughout the depths of space. Numerous alien forces are out to destroy the Imperium for good, and for that man needs protection. This comes in the form of the Imperial Guard (the first and last line of defence in the Imperium), the Sisters of Battle (specially trained women of the Imperium) and the Space Marines (Man's primary use of offence, a genetically-created warrior). They are numerous others, but these are the ones that are used most widely and greatly affect the Imperium's success in the universe.

However, the greatest enemy man must face is that from within. Every day, hundreds of mutated people are born. Some possess great psyker abilities, in which they are recruited into the Imperium. Others, either possessing massive physical defects or little psyker powers, are "cleansed" by the Inquisition in fear of an invasion of chaos daemons through the mind of the psyker.

"Mankind stands upon the brink: on the one hand lies a realm of unimaginable power, on the other awaits darkness, death, and utter damnation. Only those that follow the guiding light of the Emperor may save their souls."

- Inquisitor Daarn, Ordo Malleus


Terra, or Earth, is the centre of the Imperium. It is where it is run, where it is enforced and is the final resting place for the golden throne and the mortally wounded Emperor. The High Lords of Terra rule on behalf of the Emperor, and are therefore the twelve most powerful men in the entire known universe.

The Adeptus Terra (priesthood of Earth) also resides on the capital planet, which consist of millions and millions of loyal servants to the Imperium. They act as the high lords right hand (the Inquisition the left), and their job is to interpret and enforce the Imperium by any means possible. It is organised into many departments and sub-departments, some of which are completely unheard of to the public, or anyone who is part of any organisation lower than the priesthood on the hierarchy table.

One of the largest departments in the priesthood is the Administratum. They are responsible for every administrative job in the universe, so things such as distributing resources, filling reports, etc. They are millions of members, mostly scribes and petty officials who gained the job through heritage.

At the heart of Terra is the grand Imperial Palace. It's gates (the eternity gate) alone go one mile upwards into the sky, and are decorated with vast paintings of the Emporer and the human race itself. It is surrounded by marble pillars supporting an enormous roof, which are also adorned with pictures and paintings of the highest quality. Surrounding the path that leads to the gate are the flags of every world that has ever been an art of the Imperium, as well as famous battle markings and banners. The air is filled with a thick layer of incense, and is also the end of the pilgrimÂ’s trail, a fourteen-year journey to Terra.

Inside the palace, the ceiling goes even higher than that of the gate room. Stairs seem to carry on into nothing, with Imperium logos and symbols adorning every corner. Those of the Adeptus Custodes, who protect the palace and Emperor from unwelcome guests, guard the palace. These men are the strongest form of defence in the Imperium, and they guard the palace all their lives, and there is no doubt that they will give that up for mankind's existence.

At the heart of the palace lies the Emperor in his inner sanctum. Seated atop the golden throne, he is neither alive nor dead, merely in a state of limbo. Only a very select few have seen him, and they are sworn to secrecy with their lives.

"Every Servant has his place, no matter how lowly or modest. To know it is his greatest comfort, to excel within his greatest solace, and his master's contentment is his greater reward."

- Codex Administratum

Worlds of the Imperium

The following is a list of classes assigned to every planet and moon that is part of the Imperium. Note that Terra does not count, as it is a world of it's own. Each of these planets are usualy ruled by an Imperial Commander, who, while having to deal with heresy and mutations, may rule as they wish. They are considered very powerful indivduals, who have rule effectively over millions.

  • Hive Worlds
    These are massive worlds used to store the huge hive cities in which people live. The hives themselves are many miles in height, and are generally used as homes for the people who work in the factories and mines on the planet. The atmosphere usually gets extremely toxic; so most hives are designed so people stay indoors all their lives.
  • Civilised Worlds
    This is the most frequent type of world, generally used as a home for civilians. These are the widest in terms of variation, as there isn't any two that are the same. Schools, skyscrapers, mines, hospitals etc. are commonplace here.
  • Agricultural Worlds
    These worlds are used for the growing and selling of food to other planets. They are mostly covered in farmland, and the population is very sparse compared to other worlds.
  • Feral Worlds
    These are, for lack of a better term, undeveloped worlds. The creatures that inhabit these worlds aren't usually very intelligent, but are sometimes good sources for new Space Marine recruits. People wouldn't settle down on these worlds, as they are very primitive in relation to other types of world.
  • Dead Worlds
    As the title suggests, this type of world has little or no life at all. They are also usually inhabitable anyway. These could have been planets that were virus bombed or been subjected to a Tyranid invasion. Some are the outcome of long and horrid wars. Some are unexplainable and simply found in this state.
  • Death Worlds
    Not to be confused with dead worlds, death worlds are extremely hazardous planets that are too dangerous to support a human population. Some are variations of jungles, with wild animals and carnivorous plants making it too inhospitable for human life. It could also be covered in volcanoes, for instance. One Imperial Guard regiment, however, is based on a death world (Catachan).
  • Research Stations
    These are usually used for research as the title suggests, foe weapons testing, engineering, animal breeding, alien biology etc. They can also be used for defensive purposes, so reserve troops can be stationed here if necessary. These are usually moons, as their population doesn't grow very much.
  • Feudal Worlds
    These worlds, while not as advance as civilised words, are more advanced than feral worlds. They may be home to several political organisations and countries, and many have their own wars separate from that of the Imperium with eachb other. They are very much like medieval times, or at least before 20th century equivalent.
  • Forge Worlds
    Home of the Adeptus Mechanicus, who uncover and create the ancient weapons of war that man uses. The source of these great machines and weapons is never questioned, nor are they altered from the original blueprints. They also serve as bases of operation for the almighty Titan legions.

    "Pity those who are the left hand of the Emperor for they cannot pity, as we weep tears for the Emperor who has no tears to shed for his own eternal agony."

    - Adeptus Terra

The Enemy within

Throughout the Imperium's life, especially recently, there have been countless cases of severe mutation amongst the population. The problem with this is that this mutation serves as a gateway between the warp and the material world. This way the forces of chaos can invade the mind of the mutated, and turn them into a chaos daemon. The way the Imperium deals with this is with the Inquisition, an unrelentless authority whose job is to "cleanse" the victims (which usually involves fire). Not only are mutated people affected, but psykers who cannot control their powers are "cleansed" as well, as psychic power involves going into the warp with their mind, risking a daemon posession.

The job of the Inquisition isn’t only to deal with mutations either. It is their choice on what they have authority over. Most decide to hunt down acts of heresy against the Emperor, for example turning towards the powers of chaos in favour of the Imperium. The Inquisition is one of the most feared departments of the Imperium, having authority over nearly everyone in the universe. Their actions or motives are never questioned, as this is treated as a form of heresy. Being an Inquisitor comes with great responsibility, and with it great freedom.

"The strength of the Emperor is Humanity, and the strength of Humanity is the Emperor. If one turns from the other we shall all become Lost and the Damned."

-The Sermons of Sebastian Thor, Vol. XXVII, Ch. LXII

Warhammer 40K Main Rule Book

Many thanks to:

Im*pe"ri*um (?), n.; pl. Imperia (#). [L. See Empire.]


Supreme power; absolute dominion; empire.

2. (Law)

The right to command, which includes the right to employ the force of the state to enforce the laws. It is one of the principal attributes of the executive power.


© Webster 1913

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