Who is the historical Nicholas and how is he revered in Eastern European countries and traditions?
Saint Nicholas is the children's Saint in Belgium, the Netherlands, France, Germany, in Poland, Romania, Slovakia, Slovenia, and Ukraine, and in some parts of the Americas.
Though his helpers take on many forms, Saint Nicholas himself always appears as a bishop. The children who receive his boons don't much care (see note), and in that sense Saint Nicholas is a "secular Saint".
But they would be surprised to hear that in other European countries he is primarily a religious figure unassociated with children and gifts.
He is especially revered in the Eastern Catholic and the Orthodox Church, for his charity and justice in general, and as the patron saint of sailors and fishermen in particular, because he is supposed to have miraculously saved some mariners in a storm. As such he is celebrated in Russia, Bulgaria and in the seafaring nations of Iceland and Greece. He is the patron saint of all of Greece, and in Russia he is also dear to farmers.
But who was the historical Nicholas?
He was born in the third century in the village of Patara in what was then Greece (now Turkey). When his affluent parents died, the young orphan followed Jesus and used his inheritance to help the needy. He moved to the capital, Myra (now Demre in Turkey), to continue his charitable works and to study, and there he was probably ordained priest. He probably also made pilgrimages to Egypt and Palestine.
The only historical certainty is that, some time around the turn of the century, he was made bishop of Myra. We also know that in 303 the Roman Emperor Diocletian initiated the last and greatest of persecutions of Christians. Nicholas was imprisoned, but released after the accession of the Christian Emperor Constantine. It is also fairly certain that in 325 he attended the famous first ecumenical Council of Nicaea.
He died around 343 (supposedly on December 6, his feast day), in Myra where he was buried. His grave is supposed to have exuded a liquid, called "manna" (pure water, myrrh or oil), which was one of the many posthumous miracles that cemented his devotion.
When Asia Minor fell to the Turks in 1071, many feared they would no longer be able to make pilgrimage to Nicholas' tomb. Some sailors from Bari, Italy, decided to act, and they brought Nicholas' relics to their hometown. His relics still rest there (and manna still grows on his grave). The original shrine in Myra/Demre remains a popular place for pilgrims.