Primordial (Earth-2042)

"We meet again, young one. I am the last of those who gave you breath and shape and form, millions of years ago. I am the last of those your kind rose up against and ruthlessly destroyed. I am the last Precursor. And our answer is at hand."

- Primordial, to the Didact

The Primordial, also called the Captive or the Timeless One, and the Beast by the Tudejsa, was a mysterious being of great power once detained on Charum Hakkor, and supposedly the last surviving Precursor, its physical form altered to survive enormous stretches of time. While its body was ultimately destroyed, the Primordial would transfer its consciousness into the Gravemind, the Flood's compound intelligence, using the parasite as an instrument with which to exact its final vengeance on the Forerunners and the galaxy.

Source

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