York, in the Worlds trilogy by Joe Haldeman, is jointly governed by an elected Policy Coordinator and Engineering Coordinator. The Federated Commonwealths of America, in A Different Flesh by Harry Turtledove, is modelled heavily on the Roman Republic, governed by two chief executives styled as Censors (although the offices are more akin to the position of Consul). With each one being able to veto the actions of the other, the election of two politically-opposed Censors was intended as a check on executive power. Censors serve a single non-renewable five-year term and (alongside commonwealth governors) become life-long-serving members of the Senate upon leaving office. In Avenue 5, it is suggested that the Office of President of the United States became a duumvirate comprising a human and an artificial intelligence (reminiscent of a virtual assistant). See also Directorial system Monarchy, rule by a single person Coregency, temporary rule over a monarchy by two or more people Triumvirate, joint rule by three people Tetrarchy, joint rule by four people Decemviri, joint rule by ten people Condominium (international law) Notes References Citations Sources . . . Collective heads of state Greek words and phrases