With all of the many threads floating around concerning the Halo Universe and its games I decided to put together one all encompassing thread to discuss all things Halo related. This thread is here to serve as a resource for all the Halo fans to both discuss the Lore and the Universe and for newer fans who haven't delved into the books and such to get a better understanding of the awesome story that Bungie and Microsoft have created. Below are some links from the Official Halo Wiki that provide some great infor on the basic members, factions, races, and events in the Halo Timeline.
The Covenant
"Creatures of the Covenant, the path is broad, and we shall walk it side by side." —The Prophet of Truth
The Covenant, also referred to as the Covenant Empire was a religious hegemony of multiple alien species that controlled a large portion of the Orion Arm in the Milky Way Galaxy. Originally a mutual alliance between the San 'Shyuum and the Sangheili, the Covenant expanded to include at least six other races united in the worship of the Forerunners and the Halo Array. They waged a genocidal campaign against Humanity until they were defeated due to many factors, the most crucial of which was an internal conflict. While the Covenant's leadership was either lost during the Flood infection of High Charity or during the Battle of Installation 00, the Covenant continues to exist even after the conclusion of the war. In exactly what capacity it continues to operate remains unknown.
Known Covenant Races
Sangheili (pre-Great Schism)
The second highest caste; Sangheili, or Elites as humans call them, served as the military leaders of the Covenant before the Great Schism. While San'Shyuum often had the final say, it was the Sangheili who organized military campaigns and naval engagements. The Sangheili are the only known race permitted to build and operate starships within the Covenant, though the crews are always composed of a mix of races. Sangheili are separated into ranks based on skill and experience. To advance in rank, Sangheili must honorably earn such advancements on the battlefield.
San 'Shyuum
The highest caste in the Covenant Empire, the San'Shyuum, or Prophets as humans call them, lead the Covenant and exert complete control over all religious and political affairs. Though physically weak, Prophets wield power through absolute command of the Covenant and through scavenged Forerunner technology, leaving the task of conquest to the Sangheili and the other races. The High Prophets are addressed as "Hierarchs", "Noble Hierarchs", "Holy Ones", or "Exalted" by the other races of the Covenant.
Jiralhanae
The Jiralhanae, or Brutes as they are known by humans, are one of the newer species to the Covenant Empire and are the only race that has obtained very close to equal status to that of one of the founding "clients" of the Covenant pact, the Sangheili. The Jiralhanae took over their role as personal bodyguards of the High Prophets prior to the Great Schism and make up most of the Covenant military during the Great Schism.
Lekgolo/Mgalekgolo
Mgalekgolo, or Hunters as they are known by humans, are thought to be giant monsters, but they are actually an assemblage of worm-like entities called "Lekgolo" that create a communal, armor plated form. They always fight and travel in pairs known as "bond brothers" which technically means that not all of the colonies of worms were able to fit within one set of armor, and are the strongest of the Covenant fighting units. Many of these creatures joined the Sangheili during the Great Schism.
Unggoy
Hailing from Balaho, the Unggoy, or Grunts as they are known by humans, are the most common and lowest-placed caste of the Covenant. They breathe methane and thus must wear a large tank on their back full of the methane to survive on other planets. Relations between the Unggoy and the Kig-Yar are strained in the best of times. Many of these creatures joined the Sangheili during the Great Schism.
Kig-Yar
The Kig-Yar, or Jackals/Skirmishers as they are known by humans, are the scouts and marksmen of the Covenant military due to their superior senses. They are the second lowest Covenant caste and are about 5'6" tall and due to their lack of physical durability, they carry a portable point defense gauntlet during combat.
Yanme'e
The Yanme'e, or Drones as they are known by humans, are flying, insectoid species that served almost exclusively as engineers in the Covenant Empire. They were eventually replaced by the Huragok, and were used as aerial combatants against the UNSC, who are inexperienced at fighting airborne infantry. They became the second Covenant species with the ability of flight.
Huragok
The Huragok, or Engineers as they are known by the humans, are an artificial species created by the Forerunners. They only converse with the San 'Shyuum or individuals who learn their language. The Huragok perform the physical labor of excavating, and gathering data on Forerunner artifacts. In military terms, they are generally a non-militant race. However, at times in the Human-Covenant War they have been placed on the battlefield either as repair workers or suicide bombers. Many of these creatures joined the Sangheili during the Great Schism.
The United Nations Space Command
The United Nations Space Command (UNSC) is the military, exploratory, and scientific agency of the Unified Earth Government. The UNSC was formed in the 22nd century, a time when remnants of old cultural ideologies clashed for supremacy in the Solar system. The UNSC served mainly as overseer of United Nations military operations in space. After initiating massive militarization propaganda throughout its off-world colonies, through the UNSC, the U.N. defeated Communist and Fascist forces in a conflict generally known as the "Interplanetary War", which consisted of several side-battles that took place on Mars, the Jovian Moons and the South American rainforests. Although the Interplanetary War brought a great deal of suffering to both the colonial population and the residents of Earth, it also united humanity's military forces into a common armed force by the end of the 22nd century.
Prior to the Covenant attack on Harvest in 2525, humanity was in chaos. Battles on multiple fronts and planets evolved from a group known as the Insurrectionists who wanted independence from the Unified Earth Government. The UNSC, more specifically, the UNSCDF, constantly battled against the Insurrectionists. In an attempt to help end the long running war against the rebels, the UEG commissioned the ORION Project and later the SPARTAN-II Program, which created elite super-soldiers to combat the separatists and the insurrections they spawned. When the Human-Covenant War began and the alien invaders began decimating the Outer Colonies, these Spartans became humanity's best hope against the technological superiority of the aliens. When the war began, the UNSC became humanity's greatest protector.
This fact allowed the UNSC to override civilian rule and establish itself as humanity's primary government. Although the Unified Earth Government was more open to step down, the Colonial Administration, the arm of the UEG ruling over the colonies, resisted the UNSC's rise to power, and was thus stripped of its power.
By 2552, Earth was the last remaining major human bastion; and fell under attack by the Covenant forces. The Human-Covenant War finally came to an end after a UNSC and Covenant Separatists force eliminated the Covenant leadership and destroyed the Flood threat.
By the time the war began, humanity, and thus the UNSC, had reached Tier 3 of the Forerunner civilization achievement rank system. Humanity's rank continued to rise due to the capture of Covenant technology and equipment, which was studied and adapted for human needs. The very best and cutting edge of UNSC equipment was supplied to the SPARTAN-II project, and later less expensive but still cutting edge technology was given to the Spartan III's. One such example of innovative human technology is the energy shielding adapted and improved for use on the MJOLNIR armor.
The Forerunners
The Forerunners were an ancient race of enlightened beings whose empire -- known as the ecumene -- encompassed three million fertile worlds in the Milky Way Galaxy approximately 100,000 years ago. "Forerunner" is a literal translation of the species' name for themselves; they identified themselves as such because they believed that they held an impermanent place in the universe's Living Time and that they would be succeeded by other, better races. The Forerunners were the creators and builders of many significant installations, including the Halo Array, the Ark, and the Shield Worlds, as well as numerous lesser artifacts later found on many worlds. The Forerunners were preceded by another, even more powerful race, the Precursors. The alien faction known as the Covenant worshipped the Forerunners as gods, deriving much of their technology from Forerunner artifacts found throughout the galaxy, and believing any who defaced these relics to be heretics.
The Flood
"One single Flood spore can destroy a species." —Rtas 'Vadumee "It fed on intelligent life and in doing so, became ever more intelligent itself. The Flood was unique, it used their very strength against them." —Cortana on the Forerunner-Flood War.
The Flood (Latin Inferi redivivus meaning "the dead reincarnated" and designated LF.Xx.3273 by the Forerunners), or The Parasite as they are known to the Covenant, are a species of highly virulent parasitic organisms that reproduce and grow by consuming sentient life forms of sufficient biomass and cognitive capability. The Flood was responsible for consuming most of the sentient life in the galaxy, including the Forerunners, during the 300-year-long Forerunner-Flood War. The Flood presents the most variable faction in the trilogy, as it can infect and mutate Humans and Covenant species, such as Elites, and Brutes, into Combat Forms. They are widely considered to be the greatest threat to the existence of life, or, more accurately, biodiversity, in the Milky Way Galaxy.
Originating from an unknown world outside the Milky Way Galaxy, the Flood is an extremely adaptable, prolific and dangerous parasitic life form. The species grows and spreads by infecting other organisms, hijacking their bodies and nervous systems in order to transform them into one of many specialized Flood forms. Through infecting sentient life-forms, the Flood assimilates their memories and intelligence, and the species becomes collectively more intelligent as a result. Because of their frighteningly rapid growth rate, as long as enough hosts of sufficient biomass and intelligence are available, the Flood is effectively unstoppable.
They are the cause of the "Forerunner-Flood War", which lasted approximately 300 years. They were the reason that the Halo Array was constructed, as a last final effort by the Forerunners to preserve biological diversity in the galaxy. After exhausting every other strategic option, the Halo Array was fired, resulting in the elimination of the original source of the Flood infestation and the death of almost every sentient being in the Galaxy, save for several beings placed on the Ark by the Forerunners.
The Flood exists in a fairly stable state in the absence of a Gravemind. They lack the ability to spawn spontaneously and spread by infecting sentient life forms, specifically those that are self-aware and capable of introspection. This stage of a Flood outbreak is known as the Feral Stage.
During its Feral Stage, the Flood is only capable of local coordination through use of pheromone-based communication. Research indicates that the content of said messages are of very limited complexity. Individual Combat and Carrier Forms have access to the skills and memories of their host; however, once an outbreak establishes a viable Gravemind, the Coordinated Stage begins—and it is at this point the Flood becomes truly dangerous.
A Gravemind is the guiding intelligence of the Flood, capable of controlling all Flood forms across vast distances. With the formation of a Gravemind, the assimilated intelligence and memories of consumed hosts become part of a collective consciousness, which is capable of strategic thinking and commanding individual Flood forms in an organized manner. The control it exerts over the more mobile forms it creates is accurately likened to an entity's control over its own limbs.
Although little data exists from any adequately controlled experiment, data gathered in the field suggests that if a mobile form is removed from the influence of the Gravemind coordinating its group of origin it will revert to a Feral Stage. Insufficient data exists on whether mobile forms of one Gravemind would be influenced by another Gravemind, though logic dictates this would be the case. However, because individual Graveminds are more or less identical and are all striving for the same goal, it is likely that a distinction would be impossible to detect.
The Bestiarum states that the society of the Flood closely resembles a "utopian socialist ideal as there is no wealth, no poverty, no want, no crime, and no disease; every individual works for the advancement of the Flood as a whole". It also states that it "is unfortunate that their one overriding goal is to [butcher and consume] every other life form in the galaxy".
