Popillii Laenates was the name of a plebeian noble family in ancient Rome, notorious for cruelty and arrogance in the 2nd century BC. The name is said by Cicero to be derived from laena, the sacerdotal cloak carried by Marcus Popillius Laenas (consul 359 BC) when he went to the Forum to quell a popular rising. The family Laenas is therefore a branch of the family Popilli, but the only branch which rose to the consulship.
Famous holders of the name are:
- Marcus Popillius M.f. Laenas, four times plebeian consul in 359 BC, 356 BC, 350 BC and 348 BC, probable ancestor of the next consuls of that name
- Marcus Popillius M.f. Laenas, consul in 316 BC, possibly son of the above
- Marcus Popillius Laenas (consul 173 BC), notable for conducting a war without the consent of the Senate, and saved from trial (by the tribunes of the plebs) by his brother. Despite this scandal, he became censor in 159 BC.
- Gaius Popillius Laenas, consul in 172 BC and 158 BC, and brother of the preceding (both were sons of Publius Popillius Laenas). He was sent to Greece in 174 BC to allay the general disaffection, but met with little success. He took part in the war against Perseus, king of Macedonia (Livy xliii.17, 22). When Antiochus Epiphanes, king of Syria, invaded Egypt, Laenas was sent to arrest his progress. Meeting him near Alexandria, he handed him the decree of the Senate, demanding the evacuation of Egypt. Antiochus having asked time for consideration, Laenas drew a circle round him with his staff, and told him he must give an answer before he stepped out of it. Antiochus thereupon submitted.
- Marcus Popillius Laenas, consul 139 BC
- Publius Popillius Laenas, son of the preceding. When consul in 132 BC he incurred the hatred of the democrats by his harsh measures as head of a special commission appointed to take measures against the accomplices of Tiberius Gracchus. In 123 BC Gaius Gracchus brought in a bill prohibiting all such commissions, and declared that, in accordance with the old laws of appeal, a magistrate who pronounced sentence of death against a citizen, without the people's assent, should be guilty of high treason. It is not known whether the bill contained a retrospective clause against Laenas, but he left Rome and sentence of banishment from Italy was pronounced against him. After the restoration of the aristocracy the enactments against him were cancelled, and he was recalled.
- Gaius Popillius Laenas, son of preceding, commanded Roman forces at the Battle of Burdigala in 107 BC.