Lucius Tarquinius Superbus (also called Tarquin the Great or Tarquin II) was the last of the seven legendary kings of Rome, son of Lucius Tarquinius Priscus, and son-in-law of Servius Tullius. Tarquin ruled between 535 BC and 510 BC, in the years immediately before the founding of the Roman Republic. Tarquin was upset that he did not inherit the throne, and to add insult to his perceived injury, Tullius was the son of a slave. With his wife's help, he summoned the Senate and proclaimed himself to be king of Rome. Henchmen then murdered Tullius and Tarquin's wife desecrated her father's body by driving a chariot over it. To further his grip on power, he orchestrated the murders of key Senators who supported Tullius, and proceeded at once to repeal the recent reforms in the constitution, seeking to establish a pure despotism in their place. Wars were waged with the Latins and Etruscans, but the lower classes were deprived of their arms, and employed in erecting monuments of regal magnificence (and some important public works, such as the Cloaca Maxima), while the sovereign recruited his armies from his own retainers and from the forces of foreign allies.

Tarquin was approached by the Cumaean Sibyl who offered him nine books of prophecy, at an exorbitant price. Tarquin refused abruptly, and the Sibyl proceeded to burn three of the nine. She then offered him the remaining books, but at the same price. Tarquin hesitated, but refused again. The Sibyl then burned three more books, but she offered Tarquin the three remaining Sibylline oracles at the original price. Tarquin accepted. The books were consulted at many portentous moments in Roman history.

Tarquin's authority over the city was confirmed by three things. First, his levelling of the top of the Tarpeian Rock that overlooked the Forum, and the removal its ancient Sabine shrines. Second, the completion of the fortress temple to Jupiter on the nearby Capitoline Hill. Third, the fortunate marriage of his son to the daughter of Octavus Manilius of Tusculum, an alliance that secured him powerful assistance in the field. His reign was characterised by bloodshed and violence; his son Sextus Tarquinius's rape of Lucretia precipitated a revolt, which led to the expulsion of the entire family, after Tarquin had reigned twenty-five years. After he was exiled, Tarquin attempted to gain the support of other Etruscan and Latin kings, claiming that the republicanism would spread beyond Rome. Even though the powerful Etruscan lord Lars Porsena of Clusium (modern Chiusi) backed Tarquin's return, all efforts to force his way back to the throne were in vain, and he died a lonely and childless old man at Cumae in Etruria.

This article incorporates text from the public domain 1911 Encyclopædia Britannica.