Nileas (Greek: Νηλέας) is a former municipality in Euboea, Greece, named after the river Nilèas. Since the 2011 local government reform it is part of the municipality Mantoudi-Limni-Agia Anna, of which it is a municipal unit. The municipal unit has an area of 129.017 km. Population 2,261 (2021). The seat of the municipality was in Agia Anna.