Margrethe II in the context of "Cadet branch"

The House of Schleswig-Holstein-Sonderburg-Glücksburg, also known by its short name as the House of Glücksburg, is the senior surviving branch of the German House of Oldenburg, one of Europe's oldest royal houses. Oldenburg house members have reigned at various times in Denmark, Norway, Sweden, Iceland, Greece, several northern German states, and Russia. It takes its name from the family seat in Glücksburg, a small town in Schleswig-Holstein, Germany.

Current monarch King Charles III and King Harald V, former monarch Queen Margrethe II and former consorts Queen Anne-Marie of Greece and Queen Sofia of Spain are patrilineal members of cadet branches of the House of Glücksburg.

The House of Oldenburg is a German dynasty whose members rule or have ruled in Denmark, Iceland, Greece, Norway, Russia, Sweden, the United Kingdom, Livonia, Schleswig, Holstein, and Oldenburg. The current kings of Norway and the United Kingdom are patrilineal descendants of the Glücksburg branch of this house.

The dynasty rose to prominence when Count Christian I of Oldenburg was elected King of Denmark in 1448, of Norway in 1450 and of Sweden in 1457. Denmark's current monarch, King Frederik X, belongs to the Glücksburg branch of the House of Oldenburg through his mother, Queen Margrethe II.

Frederik X (Frederik André Henrik Christian, pronounced [ˈfʁeðˀʁek, ˈfʁæðˀʁæk]; born 26 May 1968) is the King of Denmark, reigning since the abdication of his mother, Margrethe II, in 2024.

Frederik is the eldest son of Queen Margrethe II and Prince Henrik. He was born during the reign of his maternal grandfather, King Frederik IX, and became Crown Prince of Denmark following his mother's accession in 1972. He received his early education privately at home and later attended Krebs School, École des Roches, and Øregård Gymnasium. He earned a Master of Science degree in political science from Aarhus University. After university, he served in diplomatic posts at the United Nations and in Paris, and he has trained in all three branches of the Danish Armed Forces.

The Danish royal family is the dynastic family of the monarch of Denmark. While some members of the Danish royal family hold the title of Prince(ss) of Denmark, descendants of Margrethe II additionally bear the title Count(ess) of Monpezat. Children of the monarch are accorded the style of His/Her Royal Highness. The King and Queen are styled Majesty.

Through his mother, Margrethe II, King Frederik X and his descendants belong to the House of Glücksburg, which is a branch of the royal House of Oldenburg. Margrethe II's children and male-line descendants also belong agnatically to the Laborde de Monpezat family, and were given the concurrent title Count/Countess of Monpezat by royal decree on 30 April 2008.

Margrethe II abdicated as Queen of Denmark on 14 January 2024, the 52nd anniversary of her accession, being the first voluntary abdication of a Danish monarch since that of Eric III in 1146.

Margrethe made the announcement of her abdication during her New Year's Eve address on 31 December 2023. On 14 January, Margrethe signed a declaration of her abdication during a meeting of the Council of State, whereafter her elder son Crown Prince Frederik succeeded to the Danish throne as King Frederik X. Per Danish state custom, the prime minister of Denmark then proclaimed the accession of the new monarch from the balcony of Christiansborg Palace.

Frederik IX (Christian Frederik Franz Michael Carl Valdemar Georg; 11 March 1899 – 14 January 1972) was King of Denmark from 1947 to 1972.

Frederik was born into the House of Glücksburg during the reign of his great-grandfather King Christian IX. He was the first child of Prince Christian of Denmark and Princess Alexandrine of Mecklenburg-Schwerin (later King Christian X and Queen Alexandrine). He became crown prince when his father succeeded as king in 1912. As a young man, he was educated at the Royal Danish Naval Academy. In 1935, he married Princess Ingrid of Sweden. They had three daughters: Margrethe, Benedikte and Anne-Marie. During Nazi Germany's occupation of Denmark, Frederik acted as regent on behalf of his father from 1942 until 1943.

Ingrid of Sweden (Ingrid Victoria Sofia Louisa Margareta; 28 March 1910 – 7 November 2000) was Queen of Denmark from 20 April 1947 to 14 January 1972 as the wife of King Frederik IX.

Ingrid was born into the House of Bernadotte as the only daughter of Crown Prince Gustaf Adolf of Sweden (later King Gustaf VI Adolf) and his first wife, Princess Margaret of Connaught. In 1935, she married Frederik, then Crown Prince of Denmark. The couple had three daughters: Margrethe, Benedikte, and Anne-Marie.