Interrex

The interrex (plural interreges) was an extraordinary magistrate during the Roman Kingdom and Republic. Initially, the interrex was appointed after the death of the king of Rome until the election of his successor, hence its name—a ruler "between kings" (Latin: inter reges). The position was retained during the Republic when both consuls were unable to assume their duties, especially holding elections. Interreges ruled for only five days, which often led several of them to be appointed in succession, the record being 15 interreges in 326 BC. They were exclusively chosen from among patrician senators, and during the Conflict of the Orders, their appointment was sometimes designed to hinder plebeians from reaching power or passing laws.

As with the dictatorship, interreges are mostly found until the time of the Second Punic War. The position was only resurrected by Sulla in 82 BC so he could become dictator, and between 55 and 52 BC, when Pompey disturbed the constitution for his own benefit.