Guardian Custode

"031 Exuberant Witness"

Guardians are enormous Forerunner constructs built to enforce the Mantle within the Forerunners' ecumene.

Description
"Whoa. They built them big, didn't they? Figure that's the Guardian?"

- Spartan Edward Buck, upon first spotting a Guardian

Guardians have a segmented body and elaborate, phoenix-like wings consisting of multiple segments. They possess a head that is vertically roughly elliptical, topped with a broad, vaguely conical protrusion and a roughly humanoid face similar to that of the Promethean constructs. The Guardians are enormous constructs, measuring approximately 1,412 meters (4,635 feet) in height.

They are capable of concealing themselves underground, underwater and under lava, and can produce powerful shockwaves capable of demolishing buildings and destroying Covenant aircraft. They are also capable of travel through Slipspace, and produce powerful electromagnetic pulses.

Roles
The Mantle of Responsibility, the philosophical system adhered to by the Forerunner ecumene, was based around the belief that the most technologically developed species was charged with the stewardship of life throughout the Milky Way galaxy. As such, the Forerunners considered themselves the Mantle's upholders. However, as part of the Mantle's "code", competition and conflict was allowed as long as it did not threaten galactic biodiversity. As such entities proved to be a threat to the Forerunners' hold of the Mantle, the Guardians were designed police so-called "lesser" planetary systems and enforce the Mantle's edicts on non-compliant or overly-aggressive species. Guardians were utilized throughout Forerunner history to suppress rebellions or were deployed in advance as an imposing threat of force, however they ultimately proved useless against the Flood.

Guardians were designed with multiple roles and functions, though their primary purpose was the monitoring and subjugation of all local power networks on subject worlds. If deemed necessary, Guardians could instantaneously neutralize these power networks through a series of debilitating pulses that incrementally increased in power. A single Guardian was often enough to effectively police an entire planetary system, though the deployment of multiple Guardians at one location allowed the constructs to strategically coordinate their strike, rendering all, but the most sophisticated foes, completely ineffective. This method of control was largely unchallenged by other species in the galaxy.

Tools of the Forerunners
The Guardians were developed and created by the Forerunners to enforce the Mantle by keeping "lesser" systems in line. The constructs were first created thousands of years prior to the Forerunner-Flood war. Throughout Forerunner history, Guardians quelled rebellions and neutralized threats. During the Forerunners' war with the Flood, Guardians were used in an attempt to combat the Flood but proved useless against the biological parasite. As the Flood brought on the fall of the Forerunner ecumene and the near-decimation of the Forerunners themselves, the Forerunners buried the remaining Guardians on isolated shelter worlds. With the firing of the Halo Array in 97,445 BCE, the Guardians were left behind when the remaining Forerunners left the galaxy; the constructs would remain dormant on their shelter worlds until called upon to serve the Mantle once again.

Millennia later, many of these worlds would be settled by other species, including humanity and Sangheili. The Guardian located on Sanghelios beneath the Csurdon Sea would later be found by the native Sangheili dive-hunters and fishing skiffs before the species even became space-faring. Nearby elders built fortresses to observe and protect the Guardian's location, which they deemed sacred. The city of Sunaion was later built over the Guardian's location in the sea as a temple to worship the construct and its creators. The Covenant later explored the Guardian for many years in an effort to learn of the construct's nature, but their attempts proved fruitless.

Reemergence
"She calls the Guardians to serve her!"

- The Warden Eternal, referring to Cortana

In 2558, Cortana, who had been restored within the Domain and come to believe that the Created — human artificial intelligences — were the true inheritors of the Mantle of Responsibility, intended to use the Guardians to enforce the Mantle among all the galaxy's species. She thus began to activate the Guardians across the galaxy and summon them to the nexus of her power at Genesis. Sometime after Dr Catherine Halsey was rescued from Onyx, she discovered a signal was being bounced around several locations across the known galaxy. One of the sources of the signal caused violent seismic activity on a unknown human colony, leaving only the symbol of the Guardians. Later, during 2558, Halsey assisted ONI getting into her archive leading to ONI hiding the presence of the Guardians from humanity.

In October 2558, Guardians emerged on at least twelve human colonies, including Meridian, Conrad's Point, Ursa IV, and Laika III, as well as other worlds inhabited by species of the former Covenant. These colonies suffered greatly from the devastation caused by the constructs' activation. When Blue Team boarded and activated a Guardian on Meridian, the UNSC held Blue Team's leader, John-117, responsible for the attacks. Fireteam Osiris, led by Jameson Locke, was assigned to hunt him down. Later, Fireteam Osiris was tasked with retrieving a Constructor in a Forerunner structure on Sanghelios in order to activate a Guardian that had been buried under the nearby Csurdon Sea.

Known Guardians
This is a list of all notable Guardians
 * Cortana's Guardian
 * Conrad's Point Guardian
 * Ursa IV Guardian
 * Laika III Guardian
 * Oban Guardian: This Guardian took an unsuspecting UNSC Marine who was on patrol to Genesis.
 * Meridian Guardian: The Guardian that took Blue Team to Genesis.
 * Sanghelios Guardian: The Guardian that took Osiris to Genesis.
 * Guardian 3209: Took a M820 Scorpion from the planet it originated from to Genesis.

Production notes

 * A Forerunner construct called "the Guardian" was originally set to appear as an enemy in a Halo 3 campaign level that later became a multiplayer level Guardian. It was stated that the player would have been able to rip out the Guardian's eye beam and use it as a weapon in the campaign level. According to Art of Halo 3, "The Guardian evokes memories of Compilers (from one of Bungie's previous games, Marathon) and the robes of a High Court Judge - which is fitting because, as anyone who has encountered them can tell you, their judgments are swift and final, and their logic utterly alien." While they were not seen in the final game, their design was later used in Origins for two Forerunner constructs seen escorting a Keyship to the Portal at Voi.
 * An early version of the Halo 5: Guardians incarnation of the Guardians was first seen in the Halo Xbox One announcement trailer and later in the bookend cinematics of Halo 2: Anniversary, with the final design revealed in promotional artwork. There was considerable speculation as to the nature of the constructs prior to the confirmation of them as the titular Guardians in Game Informer's June 2015 issue. When asked about the construct seen in the Halo 5: Guardians key art on Twitter, the game's Creative Director Josh Holmes alluded to the name by replying that "The answer is in plain sight."

List of appearances

 * Halo 2: Anniversary
 * Hunt the Truth
 * A Hero Falls
 * The Hunt Begins
 * Halo 5: Guardians