Guardian Custode

Guardians are Forerunner constructs.

Description
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, being over 1.4 kilometers 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.

History
The Guardians were created by the Forerunners to enforce the Mantle by keeping "lesser" systems in line. A single Guardian was typically deemed enough to police an entire system.

In October 2558, Guardians began to emerge in several human colonies. Eleven of these colonies, including Meridian, Conrad's Point, Ursa IV, and Laika III, suffered greatly from the devastation brought from the constructs' activation. When Blue Team was seen on Meridian during the Guardian's activation, the UNSC placed its leader, John-117, responsible for the attacks. Thus, they assigned Fireteam Osiris, led by Jameson Locke, 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.

The Guardian reactivations were the work of the resurrected Cortana, who intended to use them as instruments to enforce the Mantle among all the galaxy's species.

Behind the scenes

 * First seen in the Halo Xbox One announcement trailer and later in the bookend cinematics of Halo 2 Anniversary as well as Halo 5: Guardians 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."
 * The Guardians may have drawn inspiration from the Guardian Sentinel (or "Guardian") which was originally to be featured as an enemy in Halo 3 and has a shape roughly similar to the Guardians in Halo 5: Guardians.

List of appearances

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