Lucius Junius Brutus in the context of "Overthrow of the Roman monarchy"

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.

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.

Lucius Tarquinius Ar. f. Ar. n. Collatinus was one of the first two consuls of the Roman Republic in 509 BC, together with Lucius Junius Brutus. The two men had led the revolution which overthrew the Roman monarchy. He was forced to resign his office and go into exile as a result of the hatred he had helped engender in the people against the former ruling house.

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.