Initially, Xanthus is a billionaire arms merchant and inventor on Earth who has an arms conglomerate called Xanthus Industries. He’s in his late forties, very cocky, and typically wears very slender but effective body armor to protect and enhance his abilities. In Book Two he foments a war with Mars because he wants their infant teleportation technology (the probability field, or p-field).

In Book Three he dies the first time and is reanimated as an Assembler (beings who can animate objects), depicted here as he is assembled using molecular metal powders.