An elective monarchy is a monarchy where the ruling head is elected instead of strictly inheriting power. The manner of election, the nature of candidate qualifications, and the electors vary from case to case. Historically, it was common for elective monarchies to transform into hereditary ones (whether legally or de facto) by repeated election of the previous rulers' children, or for hereditary monarchies to acquire elective or semi-elective succession laws, particularly following dynastic crises.

Most elected monarchies practiced hereditary succession, guaranteeing that the title and office stayed within the royal family and specifying, more or less precisely, the order of succession. Many monarchies, to avoid an succession crisis, elected the next monarch when the previous one died and left no heir.

The kings of Macedon and of Epirus were elected by the army, which was similar in composition to the Ecclesia of the Demos, the assembly of all free Athenian citizens. Military service often was linked with citizenship among the male members of the royal house.^{[citation needed]}

In the ancient Roman Kingdom the kings were elected by the Roman assemblies. When a king died, the senate would appoint an interrex to oversee the election for a new king. Whilst given many titles (including "Augustus", i.e. "majestic") Octavian described himself as princeps senatus, or merely "first among senators". Thus he portrayed an illusion of being elected from the Senate.

A system of elective monarchy existed in Anglo-Saxon England (see Witenagemot).

John of England was chosen as King of England by a council of nobles and royal advisors at the death of his brother, Richard I, in 1199 because the heir by strict primogeniture, Arthur of Brittany, was a child at that time.

In 14th, 15th, late 17th and early 18th century England, the evolving relations between the Crown and Parliament resulted in a monarchy with both hereditary and quasi-elective elements – at least as between various contenders with some dynastic claim for the throne. Henry IV of England was chosen by Parliament in 1399 to replace Richard II. Richard was childless, and the Earl of March, the next in line to the throne, was a young child at the time, so Parliament bypassed him in favour of Henry, who had led a revolt against Richard. Parliament also confirmed depositions during the Wars of the Roses, as well as Henry VIII's settlements of the crown. During the Exclusion Crisis, King Charles II strongly opposed any such idea.

Following the Glorious Revolution, Parliament enacted the Act of Succession, whose effect was to disinherit the Stuarts and replace them by the Hanoverians, whose dynastic claim was far more remote. William III and Mary II were chosen by Parliament to replace James II. (Mary was James' daughter, William was James' nephew, and William and Mary were succeeded by Mary's younger sister Anne.) Parliament passed laws in the late 17th and early 18th centuries which explicitly excluded Catholics (and thus the male descendants of James II) from the order of succession. The Succession to the Crown Act 2013, replaced male-preference primogeniture with absolute primogeniture and ended disqualification of a person who married a Roman Catholic from succession.