A
royal mistress is the historical position of a
mistress to a
monarch or an
heir apparent. Some mistresses have had considerable power. These powerful mistresses have been commonly referred to as the "
power behind the throne". The prevalence of the institution can be attributed to the fact that royal marriages were until recent times conducted solely on the basis of
political and
dynastic considerations, leaving little space for the monarch's personal preferences in the choice of a mate.