Obviously, Santa Claus himself is a key character. Also, the reindeer like Rudolph would be important as they help Santa fly around. And the elves who make the toys are likely to be in the story too.
It could be that there's a new system in place at the North Pole this year for present delivery, and Santa has to hurry up to figure it all out. There may be some comical scenes with the elves trying to help him, but things keep going wrong. However, in the end, Santa manages to get everything sorted and has a successful Christmas delivery.
Santa Claus lives at the North Pole all year long, preparing for Christmas. One year, there was a big snowstorm just before Christmas Eve. But Santa wasn't worried. He and his elves worked hard to make sure all the toys were ready. When the night came, Santa set off in his sleigh. He first stopped at a small village. There was a family there that had been having a tough year. Santa left them many presents. The children woke up the next morning and were overjoyed. Santa's kindness made their Christmas a very special one.
Imagine Santa Claus is possessed by an evil spirit. He arrives at a small town on Christmas night, but instead of spreading joy, he spreads fear. His jolly laugh has turned into an evil cackle. He starts to give out 'gifts' that are actually cursed objects. For example, a teddy bear that strangles its owner in their sleep or a toy train that runs over anyone in its path. The townspeople have to figure out how to stop this possessed Santa before it's too late.
One Christmas, Santa was flying over a snowy forest. He saw a small cottage. Inside was an old lady who was all alone. Santa left her a warm shawl and some delicious cookies. She woke up to a very merry Christmas.