Elvis Presley and Martina McBride, Blue Christmas.  And can we call it Christmas until we've heard Porky Pig's version at least once? Or Cheech and Chong's Santa Claus and His Old Lady?  Must Be Santa but can it be Dylan?  Santa Claus is Coming to Town by the best of the YouTube amateurs, the amazing Fretkillr.  Leon Redbone and Dr. John's Frosty the Snowman.