Princess Elena (Helen) of Greece and Denmark was born on May 2, 1896 in Athens, the third child of the King Constantine I, King of the Hellenes and his Queen, Sophie Dorothea Ulrica of Prussia.
Helen had three brothers George, Alexander, and Paul, who were successively Kings of the Hellenes, and two sisters, Irene and Katherine.
On March 10, 1921 she married Carol, then Crown Prince of Romania, at Athens as per custom in the Greek royal family. They had only one son, Michael, King of Romania, who abdicated and was exiled from the country in 1947 when the communists took the power.
Princess Helen of Greece died at the age of 86 on November 28, 1982 in Lausanne, Switzerland where she had established her residence after exile.
As a matrilineal descendant of Victoria of the United Kingdom, she and all her female-line descendants are members of mitochondrial haplogroup H.