Question: Who is the paternal grandfather of Princess Theodora Of Greece And Denmark (1906–1969)?

Knowledge 1: Princess Theodora of Greece and Denmark (1906–1969)
Princess Theodora of Greece and Denmark (30 May 1906 – 16 October 1969) was the second child and daughter of Prince Andrew of Greece and Denmark and Princess Alice of Battenberg, and the second eldest sister of Prince Philip, Duke of Edinburgh. [SEP] Knowledge 2: Prince Andrew of Greece and Denmark
Prince Andrew of Greece and Denmark (– 3 December 1944) of the House of Schleswig-Holstein-Sonderburg-Glücksburg, was the seventh child and fourth son of King George I of Greece and Olga Constantinovna of Russia.He was a grandson of Christian IX of Denmark and father of Prince Philip, Duke of Edinburgh.He was from birth a prince of both Denmark and Greece by virtue of his patrilineal descent.He began military training at an early age, and was commissioned as an officer in the Greek army.His command positions were substantive appointments rather than honorary, and he saw service in the Balkan Wars.In 1913, his father was assassinated and Andrew's elder brother, Constantine, became king.Dissatisfaction with his brother's neutrality policy during World WarI led to his brother's abdication and most of the royal family, including Andrew, was exiled.On their return a few years later, Andrew saw service as Major General in the Greco-Turkish War (1919–1922), but the war went badly for Greece, and Andrew was blamed, in part, for the loss of Greek territory.He was exiled for a second time in 1922, and spent most of the rest of his life in France.By 1930, he was estranged from his wife, Princess Alice of Battenberg.His only son, Prince Philip, served in the British navy during World War II, while all four of his daughters were married to Germans, three of whom had Nazi connections.Separated from his wife and son by the effects of the war, Andrew died in Monte Carlo in 1944.He had seen neither of them since 1939.
Knowledge 1: Prince Andrew of Greece and Denmark
Prince Andrew of Greece and Denmark (– 3 December 1944) of the House of Schleswig-Holstein-Sonderburg-Glücksburg, was the seventh child and fourth son of King George I of Greece and Olga Constantinovna of Russia.He was a grandson of Christian IX of Denmark and father of Prince Philip, Duke of Edinburgh.He was from birth a prince of both Denmark and Greece by virtue of his patrilineal descent.He began military training at an early age, and was commissioned as an officer in the Greek army.His command positions were substantive appointments rather than honorary, and he saw service in the Balkan Wars.In 1913, his father was assassinated and Andrew's elder brother, Constantine, became king.Dissatisfaction with his brother's neutrality policy during World WarI led to his brother's abdication and most of the royal family, including Andrew, was exiled.On their return a few years later, Andrew saw service as Major General in the Greco-Turkish War (1919–1922), but the war went badly for Greece, and Andrew was blamed, in part, for the loss of Greek territory.He was exiled for a second time in 1922, and spent most of the rest of his life in France.By 1930, he was estranged from his wife, Princess Alice of Battenberg.His only son, Prince Philip, served in the British navy during World War II, while all four of his daughters were married to Germans, three of whom had Nazi connections.Separated from his wife and son by the effects of the war, Andrew died in Monte Carlo in 1944.He had seen neither of them since 1939. [SEP] Knowledge 2: Princess Anastasia of Greece and Denmark
Princess Anastasia of Greece and Denmark ("née" Nonie May Stewart; 20 January 1878 – 29 August 1923) was an American-born heiress and member of the Greek Royal Family.She was married to Prince Christopher of Greece and Denmark, the youngest child of King George I of Greece and his consort, Grand Duchess Olga Constantinovna of Russia, but was created a princess "suo jure".
Knowledge 1: Princess Theodora of Greece and Denmark (1906–1969)
Princess Theodora of Greece and Denmark (30 May 1906 – 16 October 1969) was the second child and daughter of Prince Andrew of Greece and Denmark and Princess Alice of Battenberg, and the second eldest sister of Prince Philip, Duke of Edinburgh. [SEP] Knowledge 2: Princess Theodora of Greece and Denmark
Princess Theodora of Greece and Denmark( born 9 June 1983 in St Mary's Hospital, London), also known under her stage name Theodora Greece, is a British actress and member of the Greek royal family and Danish Royal Family.She is currently ninth in the line of succession to the defunct Greek throne.

Answer: George I of Greece