66 BC

By place

Roman Republic

• Consuls: Manius Aemilius Lepidus and Lucius Volcatius Tullus.
• Catiline accused of conspiring against the Roman Republic with Autronius and the younger Sulla.
• The alliance between Mithridates VI of Pontus and Tigranes II of Armenia is broken.
• Tigranes II is forced to surrender, by a payment of 6,000 talents, and is reinstated by Pompey as a "friend of the Roman people" to hold Armenia as a buffer zone.
• Battle of the Lycus: Pompey the Great decisively defeats Mithridates VI, effectively ending the Third Mithridatic War.
• Gaius Antonius elected Roman praetor.
• The lex Manilia, supported by Cicero gives Pompey command over all of Asia.
• Cicero becomes praetor in Rome.

  Judea

• Aristobulus II becomes king and high priest of Judea, until 63 BC.