Lupus Protospatharius Barensis was the reputed author of the Chronicon rerum in regno Neapolitano gestarum (also called Annales Lupi Protospatharii), a precise history of the Mezzogiorno from 805 to 1102. He has only been named as the author since the seventeenth century. Lupus, along with two other Bariot chronicles, the Annales barenses and the Anonymi barensis chronicon, used some lost ancient annals of Bari up to 1051. William of Apulia appears to have used these same annals. Lupus also used the lost annals of Matera. Perhaps most unusual to Lupus is his dating method. He began his years in September and so places events of the latter half of a given year in the next year.