The Warhammer 40,000 universe encompasses tabletop strategy games, magazines, novels, films, and video games.
Warhammer 40K was created by Rick Priestley in 1987 as a futuristic continuation to his 1983 Warhammer Fantasy Battle tabletop game.
The universe of 40K is based on a grimly dark vision of the far-flung future (about 38,000 years from the present day), where death, war, pain, betrayal, tyranny, genocide and destruction are widespread, and more often than not the de facto way of life. Trillions of individuals, dozens of races, untold millions of planets inhabited by those vying for power, wealth, immortality and sometimes just their own base survival.
The events that take place in this harsh setting mainly concern the people and planets of the Milky Way galaxy. So far the only race that is known to have originated from outside of our own galaxy are the ravenous Tyranid aliens.
In the Warhammer 40K universe, the Imperial dating system is rather complex due to the vast quantity of history that has been recorded over such a stretch of time, as this date format will be used in this wiki, a brief explanation will be offered.
As an example of what you might see mentioned later on (the following standard Earth dates are in AD):
945.M2 (year/millennium) = 1945
001.M3 = 2001
012.M31 = 30,012
The first intelligent beings present in the Milky Way galaxy, they have been fighting a near-eternal war with the Old Ones for control over the entire galaxy, and the delicious life force it contains. They make use of advanced non-psychic technologies, and despise all use of the Immaterium and the Warp.
An advanced cold-blooded reptilian race, they created the Eldar and Slann races, discovered the Immaterium, and forged the first interstellar empire in known space. They had been fighting the C'tan and their Necron pawns for millions of years, before fleeing the galaxy entirely.
Necrontyr & Necrons
The first humanoid race existent in the Milky Way, they were tricked by the C'tan into becoming their slaves, the Necrons, whom they serve to this day. They went into hibernation on various different 'tomb worlds' after the Old Ones left the galaxy. The Necrontyr were transformed into Necrons, losing their flesh and souls and made into mechanical undead warriors, as they're seen in current Warhammer 40,000.
Advanced humanoid race created by the Old Ones, in order to battle against the C'tan. They continued the work their creators had made on Warpspace travel, and refined the Webway system, eventually allowing them access to instantaneous travel across the galaxy without using the Warp at all. The Eldar are a cunning and highly technological people, though they are few in number due to a mass hysteria that befell their people in M29, resulting in the awaking of the Chaos God Slaanesh.
Born from the physic imprint of all intelligent life in the galaxy, whereas the Immaterium had once been fairly tranquil and rarely travelled by the minds of the living, the collective impression made by the Eldar and humanity allowed them to manifest inside the Wrap.
Nurgle (Lord of Plague), Khorne (Blood God), and Tzeentch (Changer of Ways) were born just after Earth's Neolithic period, with Slaanesh (Dark Prince of Pleasure) only manifesting when the Eldar empire fell, circa M29.
The twisted and malign kindred of the ancient Eldar race, they have wholly turned themselves over to the side of Chaos, specifically the Prince of Pleasure, Slaanesh. Between the trillions that were killed during the Fall, only a handful of living Eldar remain in the galaxy, the ones that have turned to the dark side revel in torture, inflicting pain on each other (as well as themselves), brutal and sadistic hedonism , physical and psychological torment.
Orks are a primitive and blood thirsty race that run rampant throughout the galaxy.
Orks are asexual, releasing spores off of their body that turn into other Orkoid races. (Orks, Gretchin, or Squigs.) They are a symbiosis of fungi and flesh that work perfectly for what their entire culture is based upon, which is war. The Fungi provides a hard shell around the few vital organs they have, making them harder to kill, and naturally resistant to damage.
Orks are usually split up into clans, though there are only a few major clans, there are an uncountable number of smaller clans that are constantly being made and disbanded.
The Ork hierarchy is simple, depending simply on whoever is the biggest and the strongest. The more Orks fight and kill the larger they grow, so either the luckiest or the most skillful Ork would eventually rise to the top of the food chain in an Ork society.
Some Orks have information programmed into their DNA. These are called Oddboyz. Oddboyz can do a varying number of things, whether it be a Mek Boy who naturally understands the mechanics of vehicles and technology, or a Painboy who is born with and understand of the Ork body and medicine.
Imperium of Man
Founded by the Immortal God-Emperor and Master of all Mankind, he played a subtle part in guiding humanity for tens of thousands of years. It was his foreknowledge of the birth of the Chaos God, Slaanesh, that led to his decision to take direct control of uniting and advancing the entire Human race from M15 onwards. Humanity has become the most numerous race in the galaxy; however, they are beset on all sides by a multitude of enemies: The four Chaos Gods and their millions of followers, Tyranids, mutants, Demons, Eldar, Tau, heretics, Dark Eldar, Orks, rouge psykers, and most recently, Necrons.
A brief timeline of the events that have occurred thus far:
The Necrontyr and the Old Ones
The Necrontyr were losing the ancient war they were waging with the Old Ones, mainly due to the Old Ones' hugely powerful psychic abilities and more advanced technology, they contact the intelligent energy beings called the C'tan for aid. In turn, the C'tan have the Necrontyr create exoskeletons for them from the living metal called necrodermis so that they can interact with solid matter. The C'tan also trick the Necrontyr into transferring their own consciousnesses into robotic bodies created from necrodermis which ultimately results in their becoming the C'tan's new race of non-sentient slaves called the Necrons. The newly-created Necrons then purge almost all life from the Milky Way in order to feed the C'tan.
Birth of the future God-Emperor of Mankind
Somewhere in central Anatolia (Turkey, as it is known today) after all the known shamans of the Earth (those few members of humanity blessed with psychic abilities at this point in mankind's history) collectively commit suicide and combine their life energies within the Warp into a single soul that is reincarnated in the body of one extraordinary human being, the most potent psyker in the Milky Way galaxy, who will also prove to be immortal and thus the leader of the Imperium of Man.
8,000 BC to 1,400 AD
Birth of the Ruinous Powers aka Chaos
These entities, colloquially called the Chaos Gods, were created and empowered by the collective psychic imprint of humanity and the other intelligent races of the Milky Way galaxy on the once tranquil Immaterium, transforming it into the daemon-haunted nightmare that is the Warp of today. They are the manifest forms of negative energy that has been accumulated over the tens of thousands of years of sentient life roaming the galaxy.
1 AD to 14,000 AD
The Age of Terra aka the Age of Progress
Humanity advanced from a pre-industrial Iron Age culture to become a star-spanning civilization. During the long years of the Age of Terra, humanity comes to dominate the Earth culturally and technologically; eventually the Solar System is colonised once the necessary inter-planetary transportation and terraforming technology is developed early on in the 3rd Millennium.
Mankind moves on to colonise Mars and then the moons of Jupiter, Saturn and Neptune; advanced fusion and anti-matter propulsion technology is developed which eventually allows humanity to enter into interstellar travel. Thusly, did mankind's colonization begin in other star systems. By the end of the 15th Millennium humanity begins to use sub-light spacecraft, at first only nearby star systems can be reached and the human colonies established on them must survive as independent states since they are separated from Earth by up to ten generations of travel time.
Almost nothing of this period's events is known to current Imperial historians, though it is known that the Emperor was alive and on Earth throughout this period, disguising his true abilities and immortal nature as he moved from identity to identity, always trying to improve and better humanity as a whole, physically, technologically, intellectually and spiritually.
14,000 AD to 23,000 AD
The Dark Age of Technology
23,000 AD to 28,000 AD
The Age of Strife
The Horus Heresy
The video games
Dawn of War
The campaign was driven by an excellent story and characters. The 4 initial races wer e Space Marine , Ork , Eldar and Chaos . The game also featured Online matchmaking via Gamespy.
Winter Assault - Featured a story driven campaign and excellent characters, the addition being the Imperial Guard .
Dark Crusade - The design philosophy changed here, instead of a story driven campaign, they now switched to a meta-map conquering a planet with lore background for each milestone within campaign. It also allowed the campaign to be played with any of the 7 races. The additions were Tau and Necron.
Soulstorm - Relic did not work on this game and handed it over to Iron Lore. This expanded the previous meta map into 4 worlds to be conquered. The additions were the Sisters of Battle and Dark Eldar . The multiplayer received a slight improvement in the form of online medals for certain achievements.
Dawn of War II
Released in 2009 by Relic, this time it was moved across to a new much improved engine. The old base building was removed in favour of small squad tactics. The meta map and story driven campaign were both merged together, the multiplayer was also overhauled this time to use Windows Live, it also featured GFWL achievements. The four races were Space Marine, Ork, Eldar, and Tyranid.
The first expansion was Chaos Rising, it introduced the Chaos forces as the new race to fight against during the campaign. The expansion follows in the same style as DoW II, with branching paths and additional objectives being displayed on an open world map. Most of the old characters from the previous game reprise their roles, with some new additions such as the Librarian, Jonah Orion.
There are many Warhammer 40k books out there, thought only one series of Warhammer 40k literature (The Horus Heresy) is that popular.
The Horus Heresy Series
The Horus Heresy series is an ongoing set of novels that describe how the Emperor's most beloved son, Horus, was corrupted by the dark powers of Chaos, and his betrayal of the Emperor.
Horus Rising - Dan Abnett (April 2006)
False Gods - Graham McNeill (June 2006)
Galaxy in Flames - Ben Counter (Oct 2006)
The Flight of the Eisenstein - James Swallow (March 2007)
Fulgrim - Graham McNeill (July 2007)
Descent of Angels - Mitchel Scanlon (October 2007)
Legion - Dan Abnett (March 2008)
The Dark King & The Lightning Tower (Audio Book) - Graham McNeill & Dan Abnett (June 2008)
Battle for the Abyss - Ben Counter (August 2008)
Mechanicum - Graham McNeill (December 2008)
Tales of Heresy - Kyme & Priestley (April 2009)
Fallen Angels - Mike Lee (July 2009)
Raven’s Flight (Audio Book) - Gav Thorpe (Feb 2010)
A Thousand Sons - Graham McNeill (March 2010)
Nemesis - James Swallow (August 2010)
The First Heretic - Aaron Dembski-Bowden (October 2010)
Prospero Burns - Dan Abnett (January 2011)
Age of Darkness - Christian Dunn (May 2011)
The Outcast Dead - Graham McNeill (November 2011)
Deliverance Lost - Gav Thorpe (January 2012)
Know No Fear - Dan Abnett (February 2012)
The Primarchs - Christian Dunn (May 2012)
Fear to Tread - James Swallow (August 2012)
Shadows of Treachery - Christian Dunn and Nick Kyme (September 2012)
Angel Exterminatus - Graham McNeill (November 2012)
Betrayer - Aaron Dembski-Bowden (December 2012)