(Santa is the embodiment of Christmas joy and magic, so having a movie called "Best Christmas Ever" that involves him isn't necessarily a problem. However, the name "Santa" and the associated ideas of Christmas, presents, and joy are trademarks and copyrights held by Santa, and using them without permission could potentially be a violation of those rights. In general, it's best to be respectful and ask permission before using the names or images of other people or entities in creative projects.