The American version of St.Nicholas, originally from Dutch Sint(e) Klaas. The Dutch settlers in New Amsterdam (New York) brought his cult to America. This Santa has given the current myth its visual form: merry old man with red/white clothes, eight flying reindeers, living on or near North Pole, filling socks with presents, arriving through the chimney. The most important single source for Santa was the Christmas poem of Moore from year 1823 which was transmuted to image by Thomas Nast.
Actually the cult of Santa Claus incorporates many traditions Christian and pagan : Old Catholic, Scandinavian, Dutch, German, English. Sadly, its main feature nowadays is commercialism.