- In ancient Rome, a regent; a magistrate who governed during an interregnum.
- An interregent, or a regent.
- An official in Ancient Rome, who acted as single <xref>head of state</xref> during the <xref>interregnum</xref> between two <xref>consulates</xref>.
- An equivalent <xref>regent</xref> from the death of a Polish king till the <xref>election</xref> and <xref>enthronement</xref> of his successor.
- A similar <xref>interim</xref> ruler, CEO etc.