Arrian, also known as Arrian of the Mellenites, was a Donian General and one of Lord Solar Macharius' six Army Group commanders during the Macharian Crusade. Arrian and Macharius originally met during Macharius's early victories as commander of the Donian Imperial Guard during the Roxane Rebellion.
During the Crusade, Arrian had a disheveled appearance that had less to do with any imperfections in his uniform than his air of restless energy. He was a fanatic soldier, to the point where some members of the Lord Solar's entourage whispered that he was insane, while others believed he was touched by the Emperor's Light. One of his most infamous actions was ordering the execution of a million children of the heretic forces on Gamara 12.