St. Nilus of Rossano (born c. 905, Rossano, Calabria, Kingdom of Naples [Italy]—died December 29, 1005, Abbey of Santa Agata, near Rome; feast day September 26) was an abbot and promoter of Greek monasticism in Italy who founded several communities of monks in the region of Calabria following the Greek rule of St. Basil of Caesarea. A supporter of the regular successors to the papal crown in their controversies with antipopes, he also helped establish (1004) the noted abbey of Grottaferrata, near Rome, that remains today the centre of Greek monasticism and liturgy in Italy.