The Ceph (short for Cephalopods, also known as the Charybdis), are a technologically advanced alien species who arrived on Earth approximately 65 million years ago in the Crysis Universe. They are hostile towards humanity and are waging a war of extermination against them. It is speculated that they have been acting to prevent human degradation of the Earth's environment.
The Ceph originate from the Triangulum Galaxy, approximately 3 million light years from Earth. The war is started when the Alpha Ceph opens a Einstein-Rosen Bridge to their parent galaxy in order to bring their main invasion force to eradicate all humans.
Their army makes use of anti-gravity technology to fly through the air, and ice and energy-based weapons, and are capable of draining energy from almost any nearby source in order to power and repair themselves.