St. Nick is often used as another name for Santa Claus but in truth Nicholas is the original. Born in the third century a.d., Nicholas became well known for his charity to children and others. He was imprisoned by the Romans and beaten. He never renounced his faith. Later when released when Constantine became emperor, he continued his life serving God and his faith. He lived to be a very old man dying on 6 December 343. Stories of his charity to children and others spread and long after his death people still revered him with churches built in his name. Stories of miracles attributed to him emerged as well.
The Roman Catholic Church, Eastern Orthodox, Greek Orthodox, Anglican and Lutheran churches all have his feast day on their calendars (those using the Julian calendar celebrate it on 19 December). The Roman Catholic Church did not strip him of being a saint. Until 1968, every saint had a feast day that had to be celebrated in every diocese. What they did was make certain feast days optional and allow each diocese to decide whether to celebrate it or not. St. Nicholas is an optional feast day so it is up to the diocese to decide.
Stories of a mythical gift giver (often from pagan beliefs like forest elves that leave presents for nice kids) became popular in many European countries and were imported to the U.S. Various aspects from German, Dutch, and English were blended to create the character–the commercial character–of Santa Claus. There is no connection between St. Nicholas and the modern day character that lives in the North Pole, has flying reindeer, and elves to make toys. Santa Claus is a purely secular and even by some standards a pagan creation with no connection to St.Nicholas or Christianity. Remember that when someone says Santa Claus ought to be banned because is based on a religious figure.
For further information about St.Nicholas, go to Saint Nicholas Center.
By the way, there is a resurgence in celebrating the feast day. Usually children get treats (in stockings or boots) and often kicks off the Christmas season.
So what do you think? Santa Claus or Saint Nicholas?