Greece may no longer have a ruling monarchy, but its former royal house has close connections to several royal families in Europe through the late King Constantine and his wife, Queen Anne-Marie.
Denmark:
Queen Anne-Marie was born Princess Anne-Marie of Denmark as the youngest child of King Frederick IX and Queen Ingrid. Her older sister, Margrethe, is the current Queen of Denmark. Thus, the Greeks are closely related to the Danes through Anne-Marie. Crown Prince Pavlos of Greece is first cousins with Crown Prince Frederik of Denmark and counts Margrethe as one of his two aunts with the title of queen.
As recently as last summer, the Danes, Greeks and the Sayn-Wittgenstein-Berleburg gathered in Denmark for a family reunion at Gråsten Palace. Queen Margrethe’s two sons, Crown Prince Frederik and Prince Joachim (and their spouses), were joined by their Greek cousins, Princess Alexia, Prince Nikolaos, Princess Theodora and Prince Philippos (and most of their spouses and partners); however, Crown Prince Pavlos and his family were not in the photos released by the Danish Royal House. The three children of Princess Benedikte, Prince Gustav, Princess Alexandra and Princess Nathalie also attended the reunion.
Of course, the Greeks hold the title of Prince/Princess of Greece and Denmark but not because of their mother. The Greeks have the title “and Denmark” as they also descend from King Christian IX of Denmark through the male line, as Constantine was Christian’s great-great grandson. Christian’s son became George I of the Hellenes in 1863.
Spain:
The Greeks are also very closely related to the Spanish Royal Family through their father. King Constantine’s older sister, Princess Sophia, married Spain’s Infante Juan Carlos; they later became King Juan Carlos and Queen Sofía (and Sophia changed the spelling of her name to the Spanish form upon marriage).
So, the five children of King Constantine and Queen Anne-Marie are first cousins with King Felipe of Spain, as well as Infanta Elena and Infanta Cristina. They count one king and two queens as their uncle and aunts.
UK:
The relationship with the British Royal Family is tied to the late Prince Philip, who was born a Prince of Greece and Denmark. Prince Philip was a first cousin to the late King Paul and a first cousin once removed to King Constantine.
The late King Constantine was also a godfather to the Prince of Wales.
The Brits and Greeks are known to be close; upon the death of Queen Elizabeth II, many of King Constantine and Queen Anne-Marie’s children posted tributes to their beloved “Aunt Lilibet,” and Princess Theodora counted her as a godmother. Prince Philip was the godfather and namesake of her younger brother, Prince Philippos. Princess Maria-Olympia, the eldest child of Crown Prince Pavlos and Crown Princess Marie-Chantal, is the goddaughter of King Charles III. Prince Constantine Alexios, the eldest son of the Crown Prince Couple, has the Prince of Wales as a godfather.
And the rest:
The Greek Royal Family is also distantly related to the other royal families in Europe, like the Belgian, Luxembourgish, Norwegian and Swedish, as they all descend from King Christian IX of Denmark. However, their relations are a bit more distant than what the Greeks share with the Danes and Spaniards, in particular.
