What is "zathras"

Zathras is the name (see below for more information) of each a group of characters in the science fiction television series Babylon 5, all portrayed by Tim Choate. There were ten of these characters who appeared on several episodes throughout the series. The name of Zathras' species and homeworld were never revealed; in " War Without End", Zathras is seen living on Epsilon III and helping take care of the Great Machine with one other member of his race, although there is no evidence that this is their actual homeworld.