Xi-Nu 73 was a Tech Priest of the Legio Cybernetica. He served as the Cybernetica Datasmith of the 9th Maniple of the Carthage Cohort. During the Great Crusade he was attached to the 1,301st Expeditionary Fleet and worked closely with the Word Bearers Serrated Sun Chapter under Argel Tal. Xi-Nu was heavily biological and typical for Tech-Adepts at the time, but nonetheless demonstrated a bond with the Serrated Sun. Xi-Nu followed the Word Bearers into rebellion against the Imperium, and Xi-Nu 73 was killed protecting Cyrene Valantion from Adeptus Custodes shortly after the Drop Site Massacre.