|Administrative region||Central Greece|
|• Municipal unit||49.9 km2 (19.3 sq mi)|
|• Municipal unit||3,017|
|• Municipal unit density||60/km2 (160/sq mi)|
|• Population||1,209 (2011)|
|Time zone||UTC+2 (EET)|
|• Summer (DST)||UTC+3 (EEST)|
Oreoi (Greek: Ωρεοί) is a village and a former municipality in Euboea, Greece. It was named after the ancient town Oreus. Since the 2011 local government reform it is part of the municipality Istiaia-Aidipsos, of which it is a municipal unit. The municipal unit has an area of 49.913 km2. Population 3,017 (2011). It is situated on the northwest coast of the island Euboea, by the Oreoi Strait that connects the Aegean Sea with the North Euboean Gulf. The small port Agiokampos, 5 km west of Oreoi, is served by ferries to Glyfa on the mainland.
The municipal unit Oreoi is subdivided into the following communities (2011 census population in square brackets):
- Oreoi [1,209]
- Kastaniotissa 
- Neos Pyrgos 
- Taxiarchis 
Oreoi was named after the ancient town Oreus, that was also known as Histiaea. Oreus was situated at the eastern edge of the present village Oreoi. Oreoi was part of the municipality of Istiaia until 1912, when it became a separate community. It was elevated to municipality status in 1997. The last mayor of Oreoi, before it was merged into the new municipality Istiaia-Aidipsos, was Ioannis Stamatiou, elected in 2006.
- "Απογραφή Πληθυσμού - Κατοικιών 2011. ΜΟΝΙΜΟΣ Πληθυσμός" (in Greek). Hellenic Statistical Authority.
- "ΦΕΚ B 1292/2010, Kallikratis reform municipalities" (in Greek). Government Gazette.
- "Population & housing census 2001 (incl. area and average elevation)" (PDF) (in Greek). National Statistical Service of Greece.
- Hellenic Ministry of Culture at odysseus.culture.gr
- "EETAA local government changes". Retrieved 29 June 2020.
- "Municipal Elections, Municipality of Oreoi, Evia, 2006 Results" (in Greek). Ministry of Internal Affairs. Retrieved 2011-01-30.