Arnulf (died 14 July 937), called the Bad () or the Evil (der Böse), was the duke of Bavaria from 907 until his death. He was a member of the Luitpolding dynasty. Arnulf was the son of Margrave Luitpold of Bavaria and Cunigunda, daughter of Berthold I, the count palatine of Swabia. After the death of his father at the 907 Battle of Brezalauspurc he followed him as ruler of the Bavarian estates around Regensburg. Arnulf died in Regensburg in 937 and is buried at St. Emmeram's Abbey.