Lucius Tarquinius Collatinus (fl. 6th century BC) was one of the four leaders of the revolution which overthrew the Roman monarchy, and became one of the first two consuls of Rome in 509 BC, together with Lucius Junius Brutus. He is also the husband of Lucretia, the noblewoman raped by Sextus Tarquinius.
Collatinus was the son of Egerius, himself the son of Aruns (son of Demaratus) brother of Tarquinius Priscus (who was the fifth king of Rome). Collatinus derived his cognomen thus; his father Egerius was placed in command of the town Collatia which had been captured by Tarquinius Priscus. Thus the son was surnamed Collatinus to indicate his place of birth or origin or nearest association.
According to legend, ancient Rome had seven kings. The last of these kings, Lucius Tarquinius Superbus, was overthrown in the year 510 BCE after his son Sextus Tarquinius had raped Collatinus's wife, Lucretia. This revolt was led by the aforementioned Lucius Junius Brutus (believed to be an ancestor of the Marcus Brutus who conspired to kill Julius Caesar almost 500 years later). After overthrowing the seventh king of Rome, the Roman Republic was founded. Lucius Tarquinius Collatinus joined Lucius Junius Brutus in the first shared consulship.
Collatinus's time as consul was brief. Livy claims that the people could not endure the rule of any of the hated race of the Tarquins, and thus the innocent Collatinus was persuaded by his colleague and the other nobles to resign his office and retire from Rome. He withdrew from Rome, taking himself and his possessions to Lavinium. His colleague, Brutus, escaped this stigma, despite also being a scion of the dynasty, because his family name was Junius and not Tarquinius. Collatinus withdrew with all his property to Lavinium, and Publius Valerius Publicola was elected in his place, who then chose Spurius Lucretius Tricipitinus, Lucretia's aging father as the other consul, upon Brutus' death.