Lucius Tarquinius Superbus in the context of Servius Tullius

The overthrow of the Roman monarchy was an event in ancient Rome that took place between the 6th and 5th centuries BC where a political revolution replaced the then-existing Roman monarchy under Lucius Tarquinius Superbus with a republic. The details of the event were largely forgotten by the Romans a few centuries later; later Roman historians presented a narrative of the events, traditionally dated to c. 509 BC, but it is largely believed by modern scholars to be fictitious.

The traditional account portrays a dynastic struggle in which the king's second son, Sextus Tarquinius, rapes a noblewoman, Lucretia. Upon revealing the assault to some Roman noblemen, she kills herself. The Roman noblemen, led by Lucius Junius Brutus, obtain the support of the Roman aristocracy and the people to expel the king and his family and create a republic. The Roman army, supporting Brutus, forces the king into exile. Despite a number of attempts by Lucius Tarquinius Superbus to reinstate the monarchy, the Roman people are successful in establishing a republic and thereafter elected two consuls annually to rule the city.

The Roman Senate (Latin: Senātus Rōmānus) was the highest and constituting assembly of ancient Rome and its aristocracy. With different powers throughout its existence, it lasted from the first days of the city of Rome (traditionally founded in 753 BC) as the Senate of the Roman Kingdom, to the Senate of the Roman Republic and Senate of the Roman Empire and eventually the Byzantine Senate of the Eastern Roman Empire, existing well into the post-classical era and Middle Ages.

During the days of the Roman Kingdom, the Senate was generally little more than an advisory council to the king. However, as Rome was an electoral monarchy, the Senate also elected new Roman kings. The last king of Rome, Lucius Tarquinius Superbus, was overthrown following a coup d'état led by Lucius Junius Brutus, who founded the Roman Republic. During the early Republic, the Senate was politically weak, while the various executive Roman magistrates who appointed the senators for life (or until expulsion by Roman censors) were quite powerful. Since the transition from monarchy to constitutional rule was most likely gradual, it took several generations before the Senate was able to assert itself over the executive magistrates. By the middle Republic, the Senate had reached the apex of its republican power. The late Republic saw a decline in the Senate's power, which began following the reforms of the tribunes Tiberius and Gaius Gracchus. After the transition of the Republic into the Principate, the Senate lost much of its political power as well as its prestige.

Sextus Tarquinius was one of the sons of the last king of Rome, Lucius Tarquinius Superbus. In the original account of the Tarquin dynasty presented by Fabius Pictor, he is the second son, between Titus and Arruns. However, according to Livy and Dionysius of Halicarnassus, he was either the third or first son, respectively. According to Roman tradition, his rape of Lucretia was the precipitating event in the overthrow of the monarchy and the establishment of the Roman Republic.

According to Roman tradition, Lucretia (/luːˈkriːʃə/ loo-KREE-shə, Classical Latin: [ɫʊˈkreːtia]; died c.  510 BC), anglicized as Lucrece, was a noblewoman in ancient Rome. Sextus Tarquinius (Tarquin), the king's son, raped Lucretia, and her subsequent suicide precipitated a rebellion that overthrew the Roman monarchy and led to the transition of Roman government from a kingdom to a republic. After Tarquin raped Lucretia, flames of dissatisfaction were kindled over the tyrannical methods of Tarquin's father, Lucius Tarquinius Superbus, the last king of Rome. As a result, the prominent families instituted a republic, drove the extensive royal family of Tarquin from Rome, and successfully defended the republic against attempted Etruscan and Latin intervention.

There are no contemporary sources of Lucretia and Tarquin’s rape of her. Information regarding Lucretia, how and when Tarquin raped her, her suicide, and the consequence of this being the start of the Roman Republic come from the accounts of Roman historian Livy and Greco-Roman historian Dionysius of Halicarnassus approximately 500 years later. Secondary sources on the establishment of the republic reiterate the basic events of Lucretia's story, though accounts vary slightly between historians. The evidence points to the historical existence of a woman named Lucretia and an event that played a critical part in the downfall of the monarchy. However, specific details are debatable and vary depending on the writer. According to modern sources, Lucretia's narrative is considered a part of Roman mythohistory. Much like the rape of the Sabine women, Lucretia's story provides an explanation for historical change in Rome through a recounting of violence against women by men.

Lucius Junius Brutus (died c. 500 BC) was the semi-legendary founder of the Roman Republic and traditionally one of its two first consuls. Depicted as responsible for the expulsion of his uncle, the Roman king Tarquinius Superbus after the rape and suicide of Lucretia, in the traditional accounts it is he who led the overthrow of the Roman monarchy. He was then involved in securing the abdication of fellow consul Tarquinius Collatinus, and the suppression of a plot to restore the Tarquinian monarchy.

He was claimed as an ancestor of the Roman gens Junia, including Decimus Junius Brutus and Marcus Junius Brutus, the most infamous of Julius Caesar's assassins. Traditions about his life may have been fictional, and some scholars argue that it was the Etruscan king Porsenna who overthrew Tarquinius. The plebeian status of the Junia gens has also raised doubts about his position as a consul and the alleged initial patrician domination of the office. Depicted as the nephew of Tarquinius, he may have symbolized the internal tensions that occurred during the transition between the monarchy and the republic.

The gens Tarquinia was a plebeian family at ancient Rome, usually associated with Lucius Tarquinius Priscus and Lucius Tarquinius Superbus, the fifth and seventh Kings of Rome. Most of the Tarquinii who appear in history are connected in some way with this dynasty, but a few appear during the later Republic, and others from inscriptions, some dating as late as the fourth century AD.

Titus Tarquinius was one of the sons of the last king of Rome, Lucius Tarquinius Superbus. According to Livy and fragments of the first Roman historian, Fabius Pictor, he was the eldest son; however, Dionysius of Halicarnassus claims he was not.

Dionysius claims that each of the brothers were regents of different towns: Titus was regent of Signia. In spite of their duties, Livy and Dionysius record that Titus and his younger brother Arruns, along with his cousin Lucius Junius Brutus travelled to consult the Delphic oracle to have an omen witnessed by the king interpreted.

Arruns Tarquinius was one of the sons of Lucius Tarquinius Superbus, the last King of Rome. Ancient sources differ as to whether he was the second or third son. In the earliest accounts, passed through fragments of the first Roman historian, Fabius Pictor, he is the third son. According to Livy and Dionysius of Halicarnassus, he is the second son. Modern historians doubt the historicity of the specific actions attributed to Arruns and other members of his dynasty, regarding them as highly embellished by later accounts.

During his father's reign, he accompanied his elder brother, Titus, and their cousin, Lucius Junius Brutus, to consult the Oracle at Delphi regarding an omen witnessed by the king. After she had interpreted the omen, the princes asked the Oracle who should succeed their father as king; her reply was that he who should first kiss his mother upon their return would succeed the king. While Titus and Arruns assumed that this meant their actual mother, Brutus correctly intuited that mother earth was intended, and so deliberately stumbled and fell upon the trio's return to Italy.

The gens Junia or Iunia was one of the most celebrated families of ancient Rome. The gens may originally have been patrician, and was already prominent in the last days of the Roman monarchy. Lucius Junius Brutus was the nephew of Lucius Tarquinius Superbus, the seventh and last king of Rome, and on the expulsion of Tarquin in 509 BC, he became one of the first consuls of the Roman Republic.

Over the next several centuries, the Junii produced a number of very eminent men, such as Gaius Junius Bubulcus Brutus, three times consul and twice dictator during the period of the Samnite Wars, as well as Marcus and Decimus Junius Brutus, among the leaders of the conspiracy against Caesar. Although the Junii Bruti disappeared at the end of the Republic, another family, the Junii Silani, remained prominent under the early Empire.

The Battle of Lake Regillus was a legendary Roman victory over the Latin League shortly after the establishment of the Roman Republic and as part of a wider Latin War. The Latins were led by an elderly Lucius Tarquinius Superbus, the seventh and last King of Rome, who had been expelled in 509 BC, and his son-in-law, Octavius Mamilius, the dictator of Tusculum. The battle marked the final attempt of the Tarquins to reclaim their throne. According to legend, Castor and Pollux fought on the side of the Romans.

The Sibylline Books (Latin: Libri Sibyllini) were a collection of oracular utterances, set out in Greek hexameter verses, that, according to tradition, were purchased from a sibyl by the last king of Rome, Lucius Tarquinius Superbus, and consulted at momentous crises through the history of the Roman Republic and the Empire.

Only fragments have survived, the rest being lost or deliberately destroyed. The Sibylline Books are not the same as the Sibylline Oracles, which are fourteen books and eight fragments of prophecies thought to be of Judaeo-Christian origin.

Demaratus (Greek: Δημάρατος), frequently called Demaratus of Corinth, was the father of Lucius Tarquinius Priscus, the fifth King of Rome, the grandfather or great-grandfather of Lucius Tarquinius Superbus, the seventh and last Roman king, and an ancestor of Lucius Junius Brutus and Lucius Tarquinius Collatinus, the first consuls of the Roman Republic.

Octavius Mamilius (died 498/496 BC) was princeps ("leader, prince") of Tusculum, an ancient city of Latium. He was the son-in-law of Lucius Tarquinius Superbus, the seventh and last king of Rome. According to tradition, the gens Mamilia was descended from Mamilia, reputedly a granddaughter of Ulysses (Odysseus) and Circe. Titus Livius described Octavius as head of one of the most distinguished families of Latium, and thus an important ally of Tarquinius.

The gens Aquillia or Aquilia was a plebeian family of great antiquity at ancient Rome. Two of the Aquillii are mentioned among the Roman nobles who conspired to bring back the Tarquins, and a member of the house, Gaius Aquillius Tuscus, was consul in 487 BC.