Schleswig-Holstein-Sonderburg-Glücksburg (German) or Slesvig-Holsten-Sønderborg-Lyksborg (or Glücksborg) (Danish), from Glücksburg in northernmost Germany, is a line of the House of Oldenburg, to which the royal house of Denmark, Norway and (formerly) Greece belongs.

This particular line helds from the Dukes of Schleswig-Holstein-Sønderborg-Beck. The last of them became Duke of Glücksburg and changed his title accordingly to Friedrich Wilhelm, Duke of Schleswig-Holstein-Sonderburg-Glücksburg. He was married to Luise Caroline, Princess of Hesse-Kassel, a granddaughter of King Frederik V of Denmark.

Neither the Dukes of Beck nor of Glücksburg were sovereign rulers - they held their lands in fief to the sovereign Dukes of Schleswig and Holstein - the Kings of Denmark and (before 1773) the Dukes of Holstein-Gottorp.

Christian, the fourth son of Friedrich Wilhelm. was chosen by the childless King Frederick VII of Denmark to be his heir, as Christian was married to Frederick's first cousin, Luise of Hesse. Wilhelm, the second son of Crown Prince Christian and Crown Princess Luise, was elected King of the Hellens on March 30, 1863 to succeed the deposed Wittelsbach Otto and took the name George I. His father became King of Denmark as Christian IX on November 15, 1863. Prince Karl, he second son of Crown Prince Frederik, Christian IX's eldest son, became King of Norway on November 18, 1905 as Haakon VII. Christian IX's daughters, Alexandra and Dagmar (who became Marie Feodorovna), married the Prince of Wales and the Tsesarevich, respectively, meaning that by 1914, descendants of Christian IX were nearly as prevalent on European thrones as those of Queen Victoria.

Kings of Denmark of the House of Schleswig-Holstein-Sonderburg-Glücksburg, 1863-present

• Christian IX of Denmark (1818 - 1906, reigned 1863 - 1906).
• Frederick VIII of Denmark (1843 - 1912, reigned 1906 - 1912).
• Christian X of Denmark (1870 - 1947, reigned 1912 - 1947).
• Frederick IX of Denmark (1899 - 1972, reigned 1947 - 1972).
• Margrethe II of Denmark (1940 -, reigned 1972 - ).

Kings of the Hellenes of the House of Schleswig-Holstein-Sonderburg-Glücksburg, 1863-1973

• George I of Greece (1845 - 1913, reigned 1863 - 1913).
• Constantine I of Greece (1868 - 1923, reigned 1913 - 1917, 1920 - 1922).
• Alexander I of Greece (1893 - 1920, reigned 1917 - 1920).
• George II of Greece (1890 - 1947, reigned 1922 - 1923, 1935 - 1947).
• Paul I of Greece (1901 - 1964, reigned 1947 - 1964).
• Constantine II of Greece (1940 -, reigned 1964 - 1973).

Kings of Norway of the House of Schleswig-Holstein-Sonderburg-Glücksburg, 1905-present

• Haakon VII of Norway (1872 - 1957, reigned 1905 - 1957).
• Olav V of Norway (1903 - 1991, reigned 1957 - 1991).
• Harald V of Norway (1937 -, reigned 1991 - ).

Other notable members include:

• Prince Philip, Duke of Edinburgh (1921 - ), grandson to George I of Greece, son to Prince Andrew of Greece, consort to Elizabeth II of the United Kingdom. All agnatic descendants of Prince Philip, including Charles, Prince of Wales, also belong to this house. Some of them hold the surname of Mountbatten-Windsor.

• Queen Sofia of Spain, wife of King Juan Carlos I of Spain is also a member of this family, as she was a Greek princess, the sister of King Constantine II.