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.