What was the name of the Gaulish chieftain defeated at the Battle of Alesia?

The Gaulish chieftain defeated at the Battle of Alesia was Vercingetorix. He was the leader of the Arverni and the most prominent commander of the large Gallic revolt against Caesar in 52 BC.

After earlier resistance, Vercingetorix withdrew to Alesia, a fortified settlement in Gaul. Caesar surrounded it with an elaborate double ring of fortifications: an inner line to contain the defenders and an outer line to block a relief army. The arrangement forced the Romans to fight both the besieged army and reinforcements arriving from outside.

The relief effort failed, famine spread inside Alesia, and Vercingetorix surrendered. His defeat marked the collapse of organized Gallic resistance, although Roman campaigns continued afterward. He is often confused with Ambiorix or Ariovistus, other leaders who fought Caesar, while Cassivellaunus resisted Caesar during the Roman expedition to Britain.