Santa Claus (also known as Father Christmas) was an Earth mythological/religious/folk/commercial figure of European origin. He is primarily recognized as a magical giver of gifts during the Christmas holiday season, although the specifics and legends vary widely from region to region.
Worf dressed up as Father Christmas for a holiday party aboard the USS Enterprise-E, after losing a bet to Jasminder Choudhury. At the same event, T'Ryssa Chen dressed as one of Santa's elves. (TNG novel: Greater Than the Sum)