The Union Flag or Union Jack is the name of the flag of the United Kingdom.

Union flag may also refer to:

Continental Union Flag, first national flag of the United States Flag of the African Union Flag of Europe, also called the Flag of the European Union Flag of the Kalmar Union Flag of the Soviet Union Flag of the Union of South Africa Flag of the United States (also called "Union") Union flag, of the Union during the American Civil War Jack of the United States, currently being called a Union Jack, is the jack of the United States Navy and essentially the canton of the United States flag Union mark of Sweden and Norway The Union Flag, newspaper published in Tennessee