Gremlins isn't exactly a Christmas movies, but it does take place at Christmas. And it has one of the best Christmas stories:
Kate: The worst thing that ever happened to me was on Christmas. Oh, God. It was so horrible. It was Christmas Eve. I was 9 years old. Me and Mom were decorating the tree, waiting for Dad to come home from work. A couple hours went by. Dad wasn't home. So Mom called the office. No answer. Christmas Day came and went, and still nothing. So the police began a search. Four or five days went by. Neither one of us could eat or sleep. Everything was falling apart. It was snowing outside. The house was freezing, so I went to try to light up the fire. That's when I noticed the smell. The firemen came and broke through the chimney top. And me and Mom were expecting them to pull out a dead cat or a bird. And instead they pulled out my father. He was dressed in a Santa Claus suit. He'd been climbing down the chimney... his arms loaded with presents. He was gonna surprise us. He slipped and broke his neck. He died instantly. And that's how I found out there was no Santa Claus.