Simonopetra Monastery (Greek: Σιμωνόπετρα, literally: "Simon's Rock"), also Monastery of Simonos Petra (Greek: Μονή Σίμωνος Πέτρας), is an Eastern Orthodox monastery in the monastic state of Mount Athos in Greece. Simonopetra ranks thirteenth in the hierarchy of the Athonite monasteries.

The monastery is located in the southern coast of the Athos peninsula, between the Athonite port of Dafni and Osiou Grigoriou monastery. While the southern coast of Athos is quite rugged in general, the particular site upon which the monastery is built is exceptionally harsh. It is built on top of a single huge rock, practically hanging from a cliff 330 metres over the sea. The monastery currently houses 54 monks.