The Elf on the Shelf is a beloved holiday tradition that involves a magical elf doll who is sent to each family by Santa Claus to monitor the behavior of the children and report back to him. In most cases, the elf leaves on Christmas Eve, but there are some variations to the tradition. Some families choose to keep their elf out until Christmas Day or even until New Year's Eve. Others prefer to keep their elf out until the end of the holiday season, which is typically around January 6th. Ultimately, the decision on when to have the elf leave is up to each individual family.