The Gauls (Latin: Galli; Ancient Greek: Γαλάται, Galátai) were a group of Celtic peoples of Continental Europe in the Iron Age and the Roman period (roughly from the 5th century BC to the 5th century AD). The area they originally inhabited was known as Gaul. Their Gaulish language forms the main branch of the Continental Celtic languages.

The Ludovisi Gaul, Roman copy after a Hellenistic original, Palazzo Massimo alle Terme.

The Gauls emerged around the 5th century BC as the bearers of La Tène culture north of the Alps. They were spread across the lands between the Seine, Middle Rhine and upper Elbe. By the 4th century BC, they had expanded over much of what is now France, Belgium, the Netherlands,[1] Switzerland, Southern Germany, Austria, the Czech Republic and Slovakia,[1] by virtue of controlling the trade routes along the river systems of the Rhône, Seine, Rhine, and Danube. They quickly expanded into Northern Italy, the Balkans, Transylvania, and Galatia.[1] Gaul was never united under a single ruler or government, but the Gallic tribes were capable of uniting their forces in large-scale military operations. They reached the peak of their power in the early 3rd century BC.

After the end of the First Punic War, the rising Roman Republic increasingly put pressure on the Gallic sphere of influence. The Battle of Telamon of 225 BC heralded a gradual decline of Gallic power during the 2nd century. Rome eventually conquered Gaul in the Gallic Wars, which took place between 58 and 50 BC.

After this, Gaul was made a province of the Roman Empire. The Gauls culturally adapted to the Roman world, bringing about the formation of the hybrid Gallo-Roman culture.