In the Roman Republic, triumviri or tresviri were commissions of three men appointed for specific tasks. There were many tasks that commissions could be established to conduct, such as administer justice, mint coins, support religious tasks, or found colonies.
Most commonly, when historians refer to Roman "triumvirs", they mean two political alliances during the crisis of the Roman Republic. The informal First Triumvirate of Julius Caesar, Pompey the Great, and Marcus Licinius Crassus was a loose political alliance arranged in 60 or 59 BC that lasted until the death of Crassus in the Battle of Carrhae in 53 BC; they had no official capacity or function as actual triumviri, and the term is used as a nickname.