Manius Aquillius (died 88 BC), a member of the ancient Roman gens Aquillia, was consul in 101 BC.

Probably a son of Manius Aquillius, consul in 129 BC, Aquillius was a loyal follower of Gaius Marius. During the election campaign for Marius's fourth consulship, Aquillius was left in command of the army in case the migrating Cimbri attacked before Marius could return to command the army himself.

Manius Aquillius played a major part during the battle of Aquae Sextiae. On the first day of battle Marius defeated the Ambrones. After defeating the Ambrones Marius had to wait for the Teutones to arrive. He used this time to sent Manius Aquillius with 4,000 troops across the river with the intention to fall on the barbarians from behind during the coming engagement. The following day, when the Teutones and Marius' legions had fully engaged, Manius and his troops attacked the barbarians in the rear and caused a lot of confusion after which the battle became a rout.^[1]

As a reward for his loyal services, Gaius Marius ran with Aquillius under a joint ticket for the consulship of 101 BC. In gratitude for their victory against the Teutones they were both elected with Aquillius as Junior Consul and Marius as Senior Consul. During his consulship, with Rome struggling with a famine caused by the slave revolt in Sicily, Aquillius was sent to Sicily to put down the revolt. Aquillius completely subdued the insurgents and was rewarded an ovation in Rome in 100 BC.^[2] In 98 BC, Aquillius was accused by Lucius Fufius of maladministration in Sicily. In the subsequent trial, he was defended by Marcus Antonius the orator, the consul of 99. Gaius Marius also showed his support. Even if there was sufficient evidence of his guilt, he was acquitted because of his bravery in the war.^[3]

In 90 BC, Aquillius was sent as ambassador to Asia Minor to restore Nicomedes IV of Bithynia, who had recently been expelled from his kingdom by Mithridates VI of Pontus. However, after achieving this, Aquillius then encouraged Nicomedes to raid Pontic territory. This prompted a furious backlash from Mithridates in 89 BC, whose counter-attack began the First Mithridatic War.^[4]

Aquillius had marched the one "legion" of auxiliaries (4,000-6,000 men) then available in Asia province against Mithridates from the west while Quintus Oppius, the governor of Cilicia, had invaded with two legions from the south.^[5] Aquillius soon found out he was seriously outnumbered; at Lake Tatta he saw 100,000 Pontic infantry waiting for him.^[5] Mithridates' forces eventually tracked and defeated Aquillius near Protostachium. Aquillius fled and attempted to make his way back to Italy. He managed to make it to Lesbos, where he was delivered to Mithridates by the inhabitants of Mytilene.^[6] After being taken to the mainland, he was then placed on a donkey and paraded back to Pergamon. On the trip, he was forced to confess his supposed crimes against the peoples of Anatolia. Aquillius's father, the elder Manius Aquillius, was a former Roman governor of Pergamon and was hated for the egregious taxes that he imposed. It was generally thought that Manius Aquillius the younger would follow in the footsteps of his father as a tax profiteer and was hated by some of the local peoples.^[7]

Aquillius was eventually executed by Mithridates by having molten gold poured down his throat.^[7] The method of execution became famous and, according to some unreliable accounts,^[8] was repeated by Parthian contemporaries to kill Marcus Licinius Crassus who was at the time the richest man in Rome and a member of the First Triumvirate.^[7]