Nonnus the Abbot was a Christian monastic leader who lived during the 6th century CE in the late antique period. He is identified as an abbot, meaning he was the head of a monastic community, though the specific location of his community and the details of his life are not recorded in major historical sources. He is a distinct figure from the much more famous Nonnus of Panopolis, the 5th-century poet.

A single work is attributed to him: a collection of "Admonitions" or "Instructions" (in Greek, Nouthesiai). This text consists of practical, ascetic advice and moral exhortations intended for monks living in a communal setting. The work survives, but it is not widely studied in modern scholarship.

According to scholars, Nonnus the Abbot represents the tradition of pastoral leadership within Eastern Christian monasticism. His significance lies in his contribution to the vast body of early Christian ascetic literature. His "Admonitions" offer a window into the spiritual disciplines and communal ideals valued in a 6th-century monastery. However, due to the overshadowing fame of his poetic namesake and the limited circulation of his own work, his historical footprint is minor compared to major monastic writers of the era.