Interrex or "inter-rex" (Latin; plural, interreges) was literally a ruler "between kings." He was in effect a short-term regent. Rome The office of Interrex's said to have been instituted on the death of Romulus, when the Roman Senate wished to share the sovereign power among themselves instead of electing a king. For this purpose the senate, which then consisted of one hundred members, was divided into ten decuries (groups); and from each of these decuries one senator was nominated. These toget… (More on Interrex)