Oropos (Greek: Ωρωπός) is a small town and a municipality in East Attica, Greece.

It is situated on the southern Euboean Gulf, opposite Eretria. Oropos is located N of Avlona and Athens, E of Thebes and SE of Chalcis. Oropos is linked with the road linking Nea Palatia and Sikamino. Oropos is also linked with the service road which links with the GR-1/E75 at its nearest interchanges. The area around Oropos supports farmlands with olive groves to the south and with some mountains to the south. South of the superhighway is the Parnitha mountain. Various businesses form the industry of Oropos, and agriculture dominates the farmlands.

The present municipality Oropos was formed at the 2011 local government reform by the merger of the following 9 former municipalities, that became municipal units (constituent communities in brackets):

Oropos was founded by colonists from Eretria; it was either located in or identical with Graea. In ancient times, it was a border city between Boeotia and Attica, and its possession was a continual cause of dispute between the two states; but ultimately it came into possession of Athens, and was always an Attic town, even during the Roman Empire. The actual harbour, which was called Delphinium, was at the mouth of the Asopus, about a mile (1.6 km) north of the city.