The subject came up recently of non-Christmas Christmas songs—that is, songs we sing this time of year that have nothing to do with Christmas. I think Jingle Bells was mentioned, although it turns out this was originally a Thanksgiving song.
My favorite is Good King Wenceslas. Many are surprised at this since it is found in hymals, so it is thought to be a Christmas hymn. It is actually a Saint Stephen’s Day hymn. After all, the first two lines are “Good King Wenceslas look’d out / On the feast of Stephen.”
Saint Stephen’s Day is December 26, so this hymn is mixed in with the Christmas hymns.
Another fellow, Saint Nicholas, has his day on December 6. His reputation as a giver of gifts also was mixed in with Christmas, but that is another story.