George I (Greek: Giorgios), born as Prince Vilhelm of Denmark, was elected King of the Hellenes in 1863 by the Great Powers. He married Grand Duchess Olga Konstantinovna of Russia, daughter of Grand Duke Constantine and a niece of Tsar Alexander II, in 1867.
Children of King George and Queen Olga (note: The Greek variations of their names appears in parentheses)
Constantine (Konstantinos), born 1868 in Athens; died 1923 in Palermo, Italy. Married Princess Sophie of Prussia in 1889, had issue.
George (Giorgios), born 1869 in Athens; died 1957 in Saint Cloud, France. Married Princess Marie Bonaparte in 1907, had issue.
Alexandra, born 1870 in Corfu; died 1891 at Ilinskoe, Moscow. Married Grand Duke Paul of Russia in 1889, had issue.
Nicholas (Nikolaos), born 1872 in Athens; died 1938 in Athens. Married Grand Duchess Helen of Russia in 1902, had issue.
Marie (Maria), born 1876 in Athens; died 1940 in Athens. Married Grand Duke George of Russia in 1900, had issue. Widowed in 1919 when Grand Duke George is killed by the Bolsheviks. Remarried in 1922 to Admiral Pericles Ioannides.
Olga (Olgha), born and died in 1880 in Athens.
Andrew (Andreas), born 1882 in Athens; died 1944 in Monte Carlo. Married Princess Alice of Battenberg in 1903, had issue.
Christopher (Kristophoros), born 1888 at Pavlovsk, Russia; died 1940 in Athens. Married Nancy Stewart Leeds in 1920. Widowed in 1923 when Nancy dies of cancer. Remarries in 1929 to Princess Francoise of Orleans, had issue.
The family of King George I and Queen Olga of Greece was generally regarded by their contemporaries as a loving one, their children having been brought up in a simple (by royal standards) and cozy environment. When their eldest son, Constantine, married Princess Sophie of Prussia in 1889, Sophie's mother, the Dowager Empress of Germany, expressed her concern over Sophie marrying into a politically unstable country like Greece. In response to this, Sophie's grandmother, Queen Victoria, saying that Constantine "comes from...loving parents and a very united, loving family. And this is a priceless blessing."
Sadly, many of George and Olga's children would face great hardship in their later lives. Constantine succeeded his father as King of the Hellenes but was forced into exile twice in his reign before dying in bitter exile in 1923. Princess Alexandra died at the age of 21 when she slipped into a coma while prematurely giving birth to her son, Dmitri. Prince Andrew was tried by a military court in 1922 and banished from Greece for life.
None of George and Olga's children lived past the age of 65 except for Prince George, who died at the age of 88.