bishop of Metz and, with Pippin I, the earliest known ancestor of Charlemagne.

A Frankish noble, Arnulf gave distinguished service at the Austrasian court under Theudebert II (595–612). In 613, however, with Pippin (Pippin I), he led the aristocratic opposition to Brunhild that led to her downfall and to the reunification of Frankish lands under Chlotar II. About the same year, he became bishop.

From 623, again with Pippin, who was by then mayor of the Austrasian palace, Arnulf was adviser to Dagobert I, before retiring (629?) to become a hermit. Arnulf's son Ansegisel married Pippin's daughter Begga; the son of this marriage, Pippin II, was Charlemagne's great-grandfather.