The poem by Seamus Heaney, written in 1975.

Act of Union 1814 forming a personal union between Sweden and Norway.

Acts of Union 1707, passed by both the Parliament of England and the Parliament of Scotland to form the Kingdom of Great Britain.

The term "act of union" is also used as a euphemism for sexual intercourse.

Laws in Wales Acts 1535–1542, passed by the Parliament of England, annexing Wales to the Kingdom of England are sometimes known as the "Acts of Union".

Act of Union 1800, passed by both the Parliament of Great Britain and the Parliament of Ireland to form the United Kingdom of Great Britain and Ireland.

South Africa Act 1909, passed by the Parliament of the United Kingdom creating the Union of South Africa, is sometimes referred to as the Act of Union.

Act of Union 1652‎, (more commonly know as the Tender of Union), annexation of Scotland by the Commonwealth of England

Act of Union 1840, passed by the Parliament of the United Kingdom, joining Upper Canada and Lower Canada (to form the Province of Canada).