The Night Before Christmas
The Night Before Christmas (also Twas the Night Before Christmas and A Visit from St. Nick) is a famous poem first published in 1823 in the Troy Sentinel and generally credited to Clement Moore.
It gave rise to many of the images now associated with the secular aspects of Christmas, describing a man woken up on Christmas Eve by "such a clatter" that he gets up to see what it is. He sees Santa Claus who, chubby and jolly, comes down the chimney, fills the stockings with toys, calls his eight reindeer by name, and rides in a sleigh. He leaves by famously wishing a "Merry Christmas to all, and to all a good night!"
Originally the greeting "Happy Christmas" was used, but many American versions of the story use "Merry Christmas."