Agrinio (Greek: Αγρίνιο, Latin: Agrinium) is the largest city and municipality of the Aetolia-Acarnania regional unit of Greece, with 96,321 inhabitants. It is the economical center of Aetolia-Acarnania, although its capital is the town of Mesolonghi. The settlement dates back to ancient times. Ancient Agrinion was 3 km northeast of the present city; some walls and foundations of which have been excavated. In medieval times and until 1836, the city was known as Vrachori (Βραχώρι).

The majority of the local population was occupied for an important period of time in the tobacco industry, from the last decades of 19th till the end of the 20th century. Big tobacco companies were founded in the city, including the famous Papastratos, alongside Panagopoulos and Papapetrou. Agrinion is also agriculturally known for its production of Agrinion olives.

According to mythology, it was built by king Agrios, son of Portheus and a great grandson of Aetolos (king of Plevron and Calydon) around 1600-1100 BC. The town, built near the banks of river Achelous (the natural border between Aetolia and Acarnania), was claimed by both states during ancient times. It was destroyed by Cassander in 314 BC.