Monastery of Komnenion, eastern Orthodox monastery in Greece

The Monastery of Komnenion stands on the wooded eastern slope of Mount Ossa between Stomio and Karitsa. Its katholikon is a wide three-conch cross-in-square church, 26 by 16 metres, with four corner chapels joined to the main building; its walls alternate brick and carved stone in bands. The 16th-century church, incorporating 14th-century parts, is built over the Komnenian-era katholikon, and its outer walls are set with ancient and Byzantine spolia.

The monastery is believed to have been founded during Emperor Justinian I's reign in the 6th century, but the present structure was rebuilt in the 11th century under Emperor Alexios I Komnenos. The main church took its current form partly in the 16th century with additions from the 14th century, while wall paintings from the 18th century remain visible today.

The monastery is also called Panagia tou Oikonomiou, after the small settlement of Oikonomio that stood nearby until it was dissolved in the 1860s, where the monastery's steward (oikonomos) lived. A 1583 note by Bishop Dionysios of Platamon on a Gospel book calls it the Monastery of Saint Demetrios, perhaps the oldest witness to that name, which may come from monks who arrived in 1578 from another monastery of Saint Demetrios.

The monastery stands on the wooded eastern slope of Mount Ossa, between Stomio and Karitsa; the approach is by local roads and the last stretch on foot. The dense forest made the site hard to reach, which is why Turkish troops rarely came up except with a large force. The old katholikon was restored in the early 2000s by the 7th Ephorate of Byzantine Antiquities with European Union funds, and the modern monastery was built around it.

The 16th-century katholikon reuses ancient and Byzantine spolia in its outer walls, and the 1758 interior frescoes survive inside. Excavations found the Komnenian-era church beneath the floor. In 1852 the French traveller Mézières left with 15 manuscripts and 20 printed books, but failed to buy the gold-lettered Gospel of Saint Achilleios, for which the monk asked 4,000 Turkish piastres.