Question: Who is Princess Elizabeth Of Greece And Denmark's maternal grandfather?
Answer: Grand Duke Vladimir Alexandrovich of Russia

Grand Duchess Elena Vladimirovna of Russia (17 January 1882 – 13 March 1957), sometimes known as Helen, Helena, Helene, Ellen, Yelena, Hélène, or Eleni, was a Russian grand duchess as the only daughter and youngest child of Grand Duke Vladimir Alexandrovich of Russia and Duchess Marie of Mecklenburg-Schwerin. Her husband was Prince Nicholas of Greece and Denmark and they were both first cousins of Emperor Nicholas II of Russia. Princess Elisabeth of Greece and Denmark (24 May 1904 – 11 January 1