Helghast

Helghast are a mutation of the Human gene. They were formed when humans colonised the planet Helghan. Atmospheric anomalies were not detected and the air scorched the Colonists lungs, damaged their eyes and caused their hair to fall out, turning them all bald. Over generations the Colonists mutated to fit their environment, giving birth to a new species, the ruthless and deadly Helghast.

Due to this, the Helghast have a deep resentment of Humans. This animosity resulted in two wars, called the First and Second Helghan Wars, the latter of which is still being fought as of Killzone: Liberation. In the first conflict the humans were victorious, but due to the toxic atmosphere of Helghan, the Humans could never eradicate their foes completely. There have been rumours that Helghast have spread and colonised several other areas, and formed independent nations since these wars, although there has been no proof of this.