Arminius (18/17 BCE – CE 21), also known as Armin or Hermann (Arminius being a Latinization, similar to Brennus) is a chieftain of the Germanic Cherusci who defeats a Roman army in the Battle of the Teutoburg Forest.

Arminius's influence holds an allied coalition of Germanic tribes together in opposition to the Romans but after defeats by the Roman general Germanicus, nephew of the Emperor Tiberius, his influence wanes and Arminius is assassinated on the orders of rival Germanic chiefs.

Arminius's victory against the Roman legions in the Teutoburg forest has a far-reaching effect on the subsequent history of both the ancient Germanic peoples and on the Roman Empire.

The Romans are to make no more concerted attempts to conquer and permanently hold Germania beyond the river Rhine.