The story of Santa Claus begins in the 4th century A.D. with the Bishop of Myra (in present-day Turkey) — a man named Nicholas. Nicholas was born into a wealthy family, but was committed to using his wealth to help the needy.
As the story goes, Nicholas learned of a poor nobleman who had no dowry (a payment given to a new husband upon marriage) for his three daughters. The nobleman was preparing to sell his daughters into slavery or prostitution. Nicholas, under cover of darkness, tossed a bag of gold through an open window, thus giving the nobleman a dowry for his eldest daughter. Nicholas did the same for the other two daughters as well, but the nobleman was on watch when Nicholas chucked the third bag of gold and recognized the previously anonymous donor. (In some versions of the story, Nicholas tossed the gold coins into the chimney, and they magically landed in stockings hung by the fire to dry. Sound familiar?)
Many other stories about the generosity and piety of Nicholas spread, and he was sainted after his death. St. Nicholas's feast day is December 6, which is still celebrated by some as a day of generosity and gift-giving. Over time, his feast day blended or merged with the Christmas celebration.
As Christianity spread across Europe, so did the stories of St. Nicholas. In the 17th century, St. Nicholas came to North America through New York City via the Dutch (remember that New York City was once called New Amsterdam), who called him Sinterklaas. Sinterklaas was often accompanied by Zwarte Piet (Black Peter), who developed from Dutch stories about Satan. Enslaved by St. Nicholas, Black Peter helped deliver gifts to good children but would whip the bad children with a rod or switch. This gave rise to the story of Santa Claus keeping a list of good and bad children.
Sinterklaas, of course, isn't a far cry from "Santa Claus," and as the Dutch in the New World intermarried, it didn't take long before "Santa Claus" became the most common and recognizable name of that Christmas-time gift-giver.
Before this time, during the Protestant Reformation, church leaders in Germany and other Protestant countries discouraged veneration of the saints, a hallmark of Roman Catholic ideology. They rightly believed that the focus of Christmas ought not be St. Nicholas, but the Christ-child — Christkindlein or Christkindel in German. The tradition of gift-giving continued (it is a birthday, after all), and, over time, Christkindel transformed into Kris Kringle, who then merged with the other December gift-giver, Santa Claus.