The Cybrids are a race of sentient robots responsible for the first Earthsiege. They are led by the first Cybrid, Prometheus, who is revered with god-like status. The Cybrids established themselves in the outer solar system after being defeated two centuries before during the first Earthsiege. Since then they have built up their strength for another bid to destroy humanity and claim Earth for their own. Like the Martian rebels, the Cybrids discover their own cache of alien weapons and adapt it to use, but their cache is inferior to the Tharsis Cache.