Monarch

A monarch is a head of state for life or until abdication, and therefore the head of state of a monarchy. A monarch usually exercises the highest authority and power in the state. Usually, a monarch either personally inherits the lawful right to exercise the state's sovereign rights or is selected by an established process from a family or cohort eligible to provide the nation's monarch. Alternatively, an individual may proclaim oneself monarch, or even usurp power, as many Ancient Greek tyrants did. If a young child is crowned the monarch, then a regent is often appointed to govern until the monarch reaches the requisite adult age to rule.

Wikipedia →