The Treveri or Treviri are a tribe of Gauls who inhabit the lower valley of the Moselle from around 150 BCE, at the latest, until their eventual absorption into the Franks.

Their domain lies within the southern fringes of the Silva Arduenna (Ardennes Forest), a part of the vast Silva Carbonaria, in what are now Luxembourg, southeastern Belgium and western Germany; its center is the city of Trier (Augusta Treverorum), to which the Treveri give their name.Celtic in language, according to Tacitus they claimed Germanic descent.

Although early adopters of Roman material culture, the Treveri have a checkered relationship with Roman power.

Their leader Indutiomarus leads them in revolt against Julius Caesar during the Gallic Wars; much later, they play a key role in the Gaulish revolt during the Year of the Four Emperors.

On the other hand, the Treveri supply the Roman army with some of its most famous cavalry, and the city of Augusta Treverorum is home for a time to the family of Germanicus, including the future emperor Gaius (Caligula).During the Crisis of the Third Century, the territory of the Treveri is overrun by Alamanni and Franks and later forms part of the Gallic Empire.Under Constantine and his 4th-century successors, Augusta Treverorum becomes a large, favored and influential city that serves as one of the capitals of the Roman Empire.

During this period, Christianity begins to succeed the imperial cult and the worship of Roman and Celtic deities as the favored religion of the city.

Such Christian luminaries as Ambrose, Jerome, Martin of Tours and Athanasius of Alexandria spend time in Augusta Treverorum.

Among the surviving legacies of the ancient Treveri are Moselle wine (introduced during Roman times) and the many Roman monuments of Trier and its surroundings.