A triumvirate (Latin: triumvirātus) is a political regime ruled or dominated by three powerful individuals known as triumvirs (Latin: triumviri). The arrangement can be formal or informal. Though the three are notionally equal, this is rarely the case in reality. The term can also be used to describe a state with three different military leaders who all claim to be the sole leader.
In the context of the Soviet Union and Russia, the term troika (Russian for "group of three") is used for "triumvirate". Another synonym is triarchy.
Originally, triumviri were special commissions of three men appointed for specific administrative tasks apart from the regular duties of Roman magistrates. The triumviri capitales, for instance, oversaw prisons and executions, along with other functions that, as Andrew Lintott notes, show them to have been "a mixture of police superintendents and justices of the peace." The capitales were first established around 290–287 BCE. They were supervised by the praetor urbanus. These triumviri, or the tresviri nocturni, may also have taken some responsibility for fire control. The triumviri or tresviri aere argento auro flando feriundo (for the casting and striking of bronze, silver and gold) supervised the issuing of Roman coins.
Three-man commissions were also appointed for purposes such as establishing colonies (triumviri coloniae deducendae) or distributing land.Triumviri mensarii served as public bankers; the full range of their financial functions in 216 BCE, when the commission included two men of consular rank, has been the subject of debate. Another form of three-man commission was the tresviri epulones, who were in charge of organizing public feasts on holidays. This commission was created in 196 BCE by a tribunician law on behalf of the people, and their number was later increased to seven (septemviri epulones).