Saint Nicholas of Myra was an Christian bishop of the 13th C (born in the once Greek town of Myra). He is also known as Nicholas the Wonderworker because of the numerous miracles attributed to his intercession.
Under old tradition fish is to be necessarily on the table on this day - usually stuffed harp or some other fish meal. Bulgarians also have meatless meals for their holiday dinner.
The Black see town of Burgas celebrate Saint Nicholas as its patron.