Olga Constantinovna of Russia
Grand Duchess Olga Constantinovna of Russia , later Queen Olga of the Hellenes , was the wife of King George I of Greece and, briefly in 1920, regent of Greece. Prince Philip, Duke of Edinburgh, is her grandson.
Olga was born at Pavlovsk Palace near Saint Petersburg onSeptember1601601851. She was the second child and elder daughter of Grand Duke Constantine Nikolaievich and his wife, Grand Duchess Alexandra, a former princess of SaxeAltenburg. Through her father, Olga was a granddaughter of Tsar Nicholas I, a niece of Tsar Alexander II and first cousin of Tsar Alexander III.
Source: Wikipedia