Forerunner (Earth-2042)

"We are Forerunners, guardians of all that exists. The roots of the galaxy have grown deep under our careful tending. Where there is life, the wisdom of our countless generations has saturated the soil. Our strength is a luminous sun towards which all intelligence blossoms, and the impervious shelter beneath which it has prospered."

- Ur-Didact

The Forerunners were an ancient sentient humanoid species of extremely technologically advanced beings whose expanse encompassed much of the galaxy. The Forerunners were universally able to wield the Force and reigned for millennia as the ascendant civilization in the galaxy until the activation of the Halo Array, their pyrrhic solution to halt the Flood, in 97,445 BBY. 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. "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", though, in time, they too would be succeeded by other, superior races. 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