USA
It started with "Twas the Night Before Christmas", a poem published anonymously in 1823 and generally attributed to Clement Clarke Moore, although the claim has also been made that it was written by Henry Livingston, Jr. The poem is largely responsible for the conception of Santa Claus including his physical appearance, the night of his visit, his mode of transportation, the number and names of his reindeer, as well as the tradition that he brings toys to children. The poem has influenced ideas about St. Nicholas and Santa Claus beyond the USA.