The Holy Monastery of Xenofontos. (Greek Ξενοφώντος) is one of the twenty monasteries located on the peninsula of Mount Athos in northeastern Greece.

The monastery is on the southwestern side of the peninsula near the Monastery of St. Panteleimon. Xenofontos ranks sixteenth in the hierarchical order on Mount Athos. The monastery is dedicated to St. George the Trophy-Bearer, and celebrates its feast day on April 23. There are 11 chapels within the monastery and 6 outside.

First mention of the founding of a monastery was in 998, while the monk Xenophon is credited with building the monastery that bears his name, in 1010. After the fall of Constantinople, Xenofontos began a period of hard times as the monastery was repeatedly destroyed by pirates and then rebuilt. Each time, rulers from eastern Europe would fund rebuilding efforts. Such attacks continued until the eighteenth century.

In the sixteenth century, a katholikon (main church) was built near the entrance to the monastery in the southern part of the grounds and dedicated to St. George the Trophy-Bearer. This church featured wall-paintings by Antonios, of the Cretan school. In the eighteenth century, the monastery began to prosper again and a new katholikon was built. It was also restored between 1817 and 1837.

The main church was built just prior to the Greek Revolution of 1821 and is in the Neo-Classical style.