Arnulf of Toul was a 9th-century Catholic bishop who served the diocese of Toul in West Francia. Born to Arnald, a palatine count under Louis the Pious, he entered the clergy under Frothaire. Following the death of his predecessor around 847 or 848, both the local clergy and the people selected him for the position, a choice later confirmed by Emperor Lothaire I. His tenure was marked by political struggles involving the imperial administration and ecclesiastical councils.