Oligarchy in the context of "Thirty Tyrants"

The Roman Republic (Latin: Res publica Romana [ˈreːs ˈpuːblɪka roːˈmaːna]) was the era of classical Roman civilisation beginning with the overthrow of the Roman Kingdom (traditionally dated to 509 BC) and ending in 27 BC with the establishment of the Roman Empire following the War of Actium. During this period, Rome's control expanded from the city's immediate surroundings to hegemony over the entire Mediterranean world.

Roman society at the time was primarily a cultural mix of Latin and Etruscan societies, as well as of Sabine, Oscan, and Greek cultural elements, which is especially visible in the ancient Roman religion and its pantheon. Its political organisation developed at around the same time as direct democracy in ancient Greece, with collective and annual magistracies, overseen by a senate. There were annual elections, but the republican system was an elective oligarchy, not a democracy, with a number of powerful families largely monopolising the senior magistracies. Roman institutions underwent considerable changes throughout the Republic to adapt to difficulties such as the creation of promagistracies to rule its conquered provinces and, after the Social War during the late Republic, the inclusion of peninsular Italians as citizens and senators.

Ephialtes (Ancient Greek: Ἐφιάλτης, Ephialtēs) was an ancient Athenian politician and an early leader of the democratic movement there. In the late 460s BC, he oversaw reforms that diminished the power of the Areopagus, a traditional bastion of conservatism, and which are considered by many modern historians to mark the beginning of the radical democracy for which Athens would become famous. These powers included the scrutiny and control of office holders, and the judicial functions in state trials. He reduced the property qualifications for holding a public office, and created a new definition of citizenship. In 461 BCE, he was assassinated. Although it remains uncertain who exactly killed him, it is believed to likely be at the instigation of his oligarch opponents. In the wake of his death, the political leadership of Athens passed to his deputy, Pericles.

The Athenian coup of 411 BC was the result of a revolution that took place during the Peloponnesian War between Athens and Sparta. The coup overthrew the democratic government of ancient Athens and replaced it with a short-lived oligarchy known as the Four Hundred.

In the wake of the financial crisis caused by the failed Sicilian Expedition of the Athenian military in 413 BC, some high-status Athenian men, who had disliked the broad-based democracy of the city-state for a long time, sought to establish an oligarchy of the elite. They believed that they could manage foreign, fiscal, and war policies better than the existing government.

Augustus (born Gaius Octavius; 23 September 63 BC – 19 August AD 14), also known as Octavian (Latin: Octavianus), was the founder of the Roman Empire, who reigned as the first Roman emperor from 27 BC until his death in AD 14. The reign of Augustus initiated an imperial cult and an era of imperial peace (the Pax Romana or Pax Augusta) in which the Roman world was largely free of armed conflict. The Principate system of government was established during his reign and lasted until the Crisis of the Third Century.

Octavian was born into an equestrian branch of the plebeian gens Octavia. Following the assassination of Julius Caesar in 44 BC, Octavian was named in Caesar's will as his adopted son and heir, and inherited Caesar's name, estate, and the loyalty of his legions. He, Mark Antony, and Marcus Lepidus formed the Second Triumvirate to defeat the assassins of Caesar. Following their victory at the Battle of Philippi (42 BC), the Triumvirate divided the Roman Republic among themselves and ruled as de facto oligarchs. The Triumvirate was eventually torn apart by the competing ambitions of its members; Lepidus was exiled in 36 BC, and Antony was defeated by Octavian's naval commander Marcus Agrippa at the Battle of Actium in 31 BC. Antony and his wife Cleopatra, the Ptolemaic queen of Egypt, killed themselves during Octavian's invasion of Egypt, which then became a Roman province.

The Athenian Revolution (508–507 BCE) was a revolt by the people of Athens that overthrew the ruling aristocratic oligarchy, establishing the almost century-long self-governance of Athens in the form of a participatory democracy – open to all free male citizens. It was a reaction to a broader trend of tyranny that had swept through Athens and the rest of Greece.

Mixed government (or a mixed constitution) is a form of government that combines elements of democracy, aristocracy and monarchy, ostensibly making impossible their respective degenerations which are conceived in Aristotle's Politics as anarchy, oligarchy and tyranny. The idea was popularized during classical antiquity in order to describe the stability, the innovation and the success of the republic as a form of government developed under the Roman constitution.

Unlike classical democracy, aristocracy or monarchy, under a mixed government rulers are elected by citizens rather than acquiring their positions by inheritance or sortition (at the Greco-Roman time, sortition was conventionally regarded as the principal characteristic of classical democracy).