King of the Westralians
Royal coat of arms of Westralia
Coat of arms of the Westralian Royal Family
Alexander der Nederlanden 1851 - 1884
Alexander I
since 1 February 1870

Style: His Majesty
Heir apparent: Theodore, Prince of Swan
First monarch: Alexander I
Formation: 1 February 1870
Residence: Stirling Palace

The monarchy of the Kingdom of Westralia, commonly referred to as the Westralian monarchy, is the constitutional monarchy of Westralia. The monarch's title is "King" (male) or "Queen" (female). The first and current monarch and head of state, Alexander I, ascended the throne on appointment by the Federal Government, replacing Queen Victoria of the United Kingdom.

The monarch and his or her immediate family undertake various official, ceremonial, diplomatic and representational duties. As the monarchy is constitutional, the monarch is limited to non-partisan functions such as bestowing honours and appointing the Prime Minister. The monarch is, by tradition, commander-in-chief of the Royal Swan Armed Forces. Though the ultimate formal executive authority over the government of the United Kingdom is still by and through the monarch's royal prerogative, these powers may only be used according to laws enacted in Parliament and, in practice, within the constraints of convention and precedent.

The Westralian monarchy traces its origins from that of the United Kingdom; the responsibilities held and rights enjoyed by the monarch are the same as those of the British monarch.

When the Realm of Westralia declared its independence from the Empire of Greater Britannia in 1869, the Federal Government soon after invited Prince Alexander of the Netherlands, the third son of William III of the Netherlands, to become the first Westralian monarch. Thus, on 1 February 1870, Alexander was crowned King, establishing the current royal family and the monarchy of Westralia.