interrex
/ˈɪntərreks/Definitions
1. noun
In ancient Rome, a temporary magistrate who governed between the expiration of one consulship and the beginning of another.
“Following the death of the consuls, a committee of interrex was appointed to oversee the election of new consuls.”
2. noun
A person who holds an office temporarily, especially in a transitional period.
“During the power vacuum, the council of interrex took control until a new government was formed.”