interrex

In ancient Rome in the time of the kings (traditionally before 510 BC), an official appointed by the senators on the death of a king to hold supreme authority until the election of his successor. Later, if both consuls died or resigned before their year of office was over, interreges were appointed for five days each until new consuls had been elected. The interrex had to be a patrician and a senator, but could be quite young.

In 52 BC, which opened without any consuls or praetors having been elected, a series of interreges had to be appointed until Pompey was finally elected sole consul to put an end to the rioting between the gangs of Milo and Clodius.