I explained why I do not believe it is wise for life long benefit to teach a child to believe in Sant Claus. BUT, there is a man whose life was perverted into the concept of Santa Claus, who is well worth learning about. His name is Saint Nicholas. He was from the nation of Turkey and lived around 280 A.D. This man was a very humble, wise, godly and sacrificially giving person who is a wonderful model and hero to hold before your children. He was a great student of God's word who was highly honored by other godly peers of his day.
His connection to Santa Claus comes from his gifts to the poor. He lived very frugally himself so that he could give more generously to the poor. He would leave gifts of money in the stockings of the poor as they hung on the fireplace mantle to dry overnight after being washed. This way he could give anonymously. It was eventually discovered that he was the benefactor and he became known as Father Christmas. There are several nice easy to read books about him. I would recommend that you read one to your children and explain that the fairy tale figure of Santa Claus was a way people changed the real truth about a man with great and honorable character who we would do well to copy in our lives. He is the one who started the tradition of gifts in stockings and maybe just maybe that's why we often have turkey for Christmas dinner?