Queen Sofia of Spain, the daughter of former King Paul of Greece and sister of Ex-King Constantine II, was an Orthodox Christian prior to her marriage in the Roman Catholic Cathedral in Athens, Greece, in 1962, to Prince Juan Carlos, who later became King of Spain; Princess Sophia of Greece converted to Roman Catholicism for her marriage.
Prince Phillip, Duke of Edinburgh, former Prince of Greece, consort of Great Britain's Queen Elizabeth II, converted from Eastern Orthodoxy to Anglicanism prior to his marriage.