The seventh and final king of Rome was Tarquinius Superbus. As the son of Priscus and the son-in-law of Servius, Tarquinius was also of Etruscan birth. It was also during his reign that the Etruscans reached their apex of power. More than other kings before him, Tarquinius used violence, murder, and terrorism to maintain control over Rome. He repealed many of the earlier constitutional reforms set down by his predecessors.

Tarquinius removed and destroyed all the Sabine shrines and altars from the Tarpeian Rock, enraging the people of Rome. The people came to object to his rule when he allowed the rape of Lucretia, a patrician Roman, at the hands of his own son. Tarquin's son, also named Tarquin, threatened Lucretia that if she refused to copulate with him, he would kill a slave, then kill her, and have the bodies discovered together, creating a gigantic conspiracy. Lucretia then told her relatives about the threat, and subsequently committed suicide to avoid any such conspiracy. Lucretia’s kinsman, Lucius Junius Brutus (ancestor to Marcus Brutus), summoned the Senate and had Tarquinius and the monarchy expelled from Rome in 510 BC.

After Tarquinius’ expulsion, the Senate voted to never again allow the rule of a king and reformed Rome into a republican government in 509 BC. Many years later during the Republican period, this strong Roman opposition to kings will be used by the Senate as a rationalization for the murder of the agrarian reformer Tiberius Gracchus. Lucius Junius Brutus and Lucius Tarquinius Collatinus, a member of the Tarquin family and Lucretia's widower, went on to become the first consuls of Rome’s new government. This new government would lead the Romans to conquer most of the Mediterranean world and would survive for the next 500 years until the rise of Julius Caesar and Caesar Augustus. Even then, the trappings of the Republic were not entirely done away with; the Republic would survive in a debased form until the Dominate.