Forerunners
The Forerunners are a race of aliens referred to in the video game Halo: Combat Evolved. Little is known about them, but certain things can be acertained from hints located in the game. The Forerunners constructed the Halos to contain the Flood (a dangerous species of mutative infection spores), but it is unknown what, specifically, is the connection between the two.
The alien race known as The Covenant is said to have originated on a planet with the Forerunners, even considering them Gods, but it is not known if this is religious propaganda or not. The Covenant have explained in the book "The Flood" that they recieved much of their technology (if not all of it) from the "Forerunners". A species in their federation of alien species called the "Prophets", who are supposedly part of a leader caste, evolved on the same planet as the Forerunners.
Some fans believe that the Forerunners are the Jjaro, an equally ancient, powerful, and absent alien race from the Marathon series of games.
