Margrethe II (Danish: Margrethe 2.; Faroese: Margreta 2.; Greenlandic: Margrethe II) (Danish pronunciation: [mɑˈɡ̊ʁæːˀd̥ə], full name: Margrethe Alexandrine Þórhildur Ingrid; born 16 April 1940) is the Queen of Denmark. She is also the supreme authority of the Church of Denmark and Commander-in-Chief of the Danish Defence Forces.

Born into the House of Glücksburg, a royal house with origins in Northern Germany, she was the eldest child of Frederick IX of Denmark and Ingrid of Sweden. She succeeded her father upon his death on 14 January 1972, having had become heir presumptive to her father in 1953, when a constitutional amendment allowed women to inherit the throne. On her accession, Margrethe became the first female monarch of Denmark since Margaret I, ruler of the Scandinavian countries in 1375–1412 during the Kalmar Union.

Having been on the Danish throne for 45 years, she is the second longest-reigning Danish monarch after her ancestor Christian IV.

In 1967, she married Henri de Laborde de Monpezat, with whom she has two sons: Crown Prince Frederik (born 1968) and Prince Joachim (born 1969).