Clement Clarke Moore 

"A Visit from St. Nicholas", also known as "The Night Before Christmas" and
“Twas the Night Before Christmas" from its first line, is a poem first published anonymously in the Troy, New York, Sentinel on December 23, 1823. It is
generally attributed to Clement Clarke Moore, although the claim has also
been made that it was written by Henry Livingston, Jr. Four hand-written
copies of the poem are known to exist, and three are in museums.

Henry Livingston, Jr.