Bituitus ( 2nd century BCE) was a king of the Arverni, a Gaulish tribe living in what is now the Auvergne region of France. The Arverni were a powerful opponent of the Roman Republic during the 3rd and 2nd centuries under the leadership of Luernios, the father of Bituitus. In 121 BCE, Bituitus was defeated by the Roman general Fabius Maximus, ending the power of the Arverni in Mediterranean Gaul, or present-day southern France. The defeat of the Arverni resulted in the establishment of the Roman province of Gallia Narbonensis.
In 121 BC, the Roman proconsul Domitius Ahenobarbus undertook a war against the Allobroges, who allied with the Arverni under Bituitus. These Gallic tribes were defeated near the town of Vindalium, the current French town of Bédarrides. After this defeat, the Allobroges and Arverni made preparations to renter battle with the Romans. Bituitus again took the field with a large army. Where the Isère (river) meets the river Rhone in the south of France, the consul Fabius Maximus, the grandson of Paullus, met them in battle in the autumn of 121 BC. The Romans were greatly outnumbered, yet managed to gain a complete victory. It was estimated that 120,000 of Bituitus' army fell in the battle.
Following his defeat, Bituitus was taken prisoner and sent to Rome, where he was sentenced by the senate to exile in Alba Fucens, one of three foreign kings known to have been held there. Bituitus' son, Congonnetiacus, was also captured, and possibly held with him at Alba. It was the last time that a foreign king was detained at Alba, and throughout the rest of the Late Republican period, kings are known to have been detained at Rome, often in the homes of high-ranking officials, and to have agitated actively in political affairs.