"The most famous reindeer of all," Rudolph has become a vital ingredient of Christmas lore for generations of children around the world, but few people recall the true genesis of the story. Fewer still would be able to explain how much the original Rudolph fable has been changed by the efforts of songwriters and animators through the decades since its 1939 conception. Yet such is the enduring popularity of this tale in its myriad forms that sociologist James Barnett declared Rudolph the twentieth-century Christmas symbol "most likely to become a lasting addition" to Christmas folklore.

Rudolph the Red-Nosed Reindeer was the brainchild of Robert L. May, a 35-year-old advertising copywriter for the Chicago-based Montgomery Ward department store. In 1939, May was commissioned by his supervisor to create an original Christmas story that the store could give away to shoppers at holiday time. May was...