The Santa Clause

Scott Calvin is a divorced advertising executive. His former wife, Laura, is now married to psychiatrist Neil Miller. Scott and Laura's son, Charlie spends Christmas Eve with his father, who burns the Christmas turkey, forcing them to eat at Denny's. After Scott reads "Twas the Night Before Christmas" to Charlie on Christmas Eve, he and Charlie are awakened that night by sounds on the roof. After confronting a man on the roof, who inadvertently falls off when Scott startles him, then vanishes leaving his Santa Claus outfit behind, they discover eight reindeer on the roof and Charlie convinces Scott to put on the suit and finish Santa's work for him. As the morning comes, the reindeer return to the North Pole to Santa's Workshop, where the head elf Bernard explains that, due to a clausical contract written on a card Scott found on Santa, in putting on the suit and entering the sleigh he has accepted the "Santa Clause" and has agreed to the responsibilities of that position. He tells a skeptical Scott that he has eleven months to get his affairs in order before reporting to the workshop at Thanksgiving permanently. Read more on Wikipedia.