Omega Hunters are major antagonists in the Extinctioners, acting as one of the series most prominent threats and the enforcers of the mysterious Invasion Force that act as the main antagonists of the first story-arc.
Omega Hunters were originally designed to be extremely massive, chunky robots in a similar manner to the Sentinels from Marvel Comics but later changed design to resemble more closely the original intent of a humanoid skeleton (albeit with some obvious modifications).
Omega Hunters are vicious, deadly machines that track down beings with powers or gifts that may be of use to the Invasion Force and give them a brutal choice - to serve or die.. if they willingly surrender they are made into Trackers (basically slaves) and forced to wear Mind-Collars that bind them to the Invasion Force, if they refuse they are executed without mercy by the Omega Hunters.
The Omega Hunters, like all other Invasion Force members, are subservient to Noah Adam Man - the main antagonist of the entire series.