She was a sister to Constantine I of Greece, and thus aunt of three kings and two queens, Constantine's three sons, who all became kings of Greece, and two of his daughters, who were queens, of Romania and (titularly) Croatia, respectively.
She was also first cousin of Tsar Nicholas II of Russia, King George V of the United Kingdom, King Christian X of Denmark, and both King Haakon VII and Queen Maud of Norway, as well as a paternal aunt of Prince Philip, Duke of Edinburgh.