Precursor (Earth-2042)

"We are the last of those who gave you breath and form, millions of years ago. We are the last of those your kind defied and ruthlessly destroyed. We are the last Precursors. And now we are legion."

- Gravemind, to Catalog

The Precursors were an advanced sentient species that preceded and were mythologized by the Forerunners. The Forerunners classified them as "Transsentient" beings, having the ability to travel among galaxies and accelerate the evolution of intelligent life. While the Precursors themselves had long since disappeared during the time of the Forerunners, evidence of their technological and architectural achievements remained scattered across not only the galaxy but also outside it, namely in the Rishi Maze.

Source

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