Melissia is a town and suburb located in the northeastern part of the Athens agglomeration in Greece. Situated approximately 12 km northeast of the Athens city centre, it lies at the southwestern foot of the Penteli mountains.
Since the local government reform of 2011, Melissia has served as the seat of the municipality of Penteli and constitutes its own municipal unit. The surrounding municipal unit covers a total area of 3.956 km2. The town is characterized primarily as a green residential area.