Quadrumvirs (Italian: quadrumviri) may refer to:
- In ancient Rome, quadrumvirus was an elective post assigned to four citizens having police and jurisdiction power. They were elected by the Senate.
- At the beginning of Italian Fascism, they were a group of four leaders that led Benito Mussolini's March on Rome in October 1922. They were all involved in the Fascist party under Mussolini and had been involved in politics and/or war for many years leading up to the Fascist dictatorship. They were:
- Michele Bianchi, a revolutionary syndicalist leader
- Emilio De Bono, a leading Italian General who had fought in World War I
- Cesare Maria De Vecchi, a member of the Italian Chamber of Deputies, as well as a colonial administrator
- Italo Balbo, a Blackshirt leader and leader of the Ferrara Fascist organisation and "heir apparent" to Mussolini's dictatorship