Margrethe II (Margrethe Alexandrine Þórhildur Ingrid, born 16 April 1940) is Queen of Denmark. Having reigned as Denmark's monarch for over 50 years, she is the world's only current queen regnant and the longest-serving current female head of state. Born into the House of Glücksburg, a cadet branch of the House of Oldenburg, Margrethe is the eldest child of King Frederick IX and Queen Ingrid. She became heir presumptive to her father in 1953, when a constitutional amendment allowed women to inherit the throne. Margrethe succeeded her father upon his death on 14 January 1972. On her accession, she became the first female monarch of Denmark since Margrethe I, ruler of the Scandinavian kingdoms in 1376–1412 during the Kalmar Union. In 1967, she married Henri de Laborde de Monpezat, with whom she had two sons: Crown Prince Frederik and Prince Joachim.
