"A Visit from St. Nicholas" (often called "The Night Before Christmas" and "'Twas the Night Before Christmas", from its first line) is a poem, first published anonymously under the title "Account of a Visit from St. Nicholas", in 1823. Authorship has been attributed to Clement Clarke Moore, who claimed authorship in 1837; but it has also been suggested that Henry Livingston Jr. wrote it. (Wikipedia, CC BY-SA 4.0)