An evil demon and a member of the Brothers Djinn.
Calythos is a demon from Earth's distant past. He describes himself as a "child of fire" and his body has a theme of lava, both hot and cold, being black with glowing red cracks. His head is like the skull of an animal with the jaw almost detached. He intends to return the Earth to its "pre-human glory" by flooding it with magma after which he and the other Brothers Djinn will rule over it. To achieve this, he carries a flaming sword (he calls it a scimitar and is stored in a scabbard on his back) which only has to be placed in the ground and levered side-to-side to release the lava. In addition, he can absorb a victim into himself and make use of their powers, and when he does this to Parasite he is able to steal the powers of his superhero opponents - and their weaknesses. When flying at speed he has the appearance of a flaming meteorite.
The volcano that Calythos makes to rise from the sea becomes the site for the Justice League's new base: the Watchtower.