Precursor

The Precursor Race is a highly advanced and ancient space-faring alien race that arrived on Planet 4546B approximately one thousand years ago, searching for a cure for the Kharaa Bacterium. Most information surrounding them is currently unknown.

The ulterior motive of the Precursors was to stop the Kharaa Bacterium from destroying their race, which was a bacterium that they discovered on an unknown planet. Their plans failed and Kharaa was released onto 4546B. It seems that this was the main cause of the death of the Precursors, who were then reborn in the warper initiative.

Biology
No Precursor has ever been seen, so nothing is known of their physical appearance. Of the few things known about their race, one is that they lived for an extremely long time, shown in a data bank entry by the mention of a ninety-six year old Precursor being considered very young. The same individual was around 700 Earth-years old when it died due to Kharaa infection. It is likely that they are a lot larger than humans, based on the size of their bases and the objects within them, a prime example being the height of the surgical tables found in the Disease Research Facility on 4546B. For use as a surgical table they would most likely come up to around the torso of the surgeon, by this it can be estimated that the Precursor race would have averaged between seven and eight feet in height. The use of the word "seed" in reference to the unborn form of a Precursor possibly implies plant-like biology, though it is equally possible that seed could refer to an animal ovum. Imperfect translation may also be the reason behind this. when they died the then transferred there souls into the different Types of warpers. they had created and proceed to build machines and attempt to eliminate the Khaara. Until today, no communication has been made with the inferior survivor genomes.

Contact with other species
The Precursors are known to have scavenged technology from other races. All but one of the relics held by them were taken from other races, some of these races even more ancient than themselves. One of the relics is a sword from Earth, showing that the Precursors visited the planet and possibly even made contact with humans at some point.