Forerunner (Earth-2915)

The forerunners (Latin Primoris prognatus, meaning "first born") were an ancient species of extremely technologically advanced beings whose expanse encompassed much of the Milky Way galaxy. The forerunners reigned for millennia as the ascendant civilization in the galaxy until the activation of the Halo Array, their pyrrhic solution to halt the xenomorphs, in 97,445 BCE. Although they themselves are essentially extinct, evidence of their existence remained, spread across the galaxy in the form of numerous creations, installations and artifacts.

The forerunners took upon themselves the role of caretakers of the galaxy, and believed that this "Mantle" had been passed down to them. Before their disappearance from the galaxy, the forerunners would name humanity their successors, identifying them with the title "Reclaimer".

In modern history, the alien hegemony known as the Covenant mythologized the forerunners and revered them as gods, deriving much of their own technology from forerunner artifacts found throughout the galaxy, and held that any who defaced these relics were heretics.

Source

 * https://www.halopedia.org/Forerunner