Arn was a 9th-century bishop of Würzburg who served from 855 until his death in 892. A student of Bishop Gozbald, he was chosen to succeed his mentor. Known as a warrior-prelate, he participated in various military conflicts to defend German territories. Throughout his career, he remained an influential figure within the East Frankish government, serving under rulers such as Louis the German, Charles the Fat, and Arnulf of Carinthia.