The number of reindeer characters, and the names given to them (if any) vary in different versions, but those frequently cited in the United States and Canada are the eight listed in Clement Clarke Moore's 1823 poem A Visit from St. Nicholas, the work that is largely responsible for the reindeer becoming popularly known.
While variations exist in the number and names of reindeer characters, the eight mentioned in Clement Clarke Moore's 1823 poem "A Visit from St. Nicholas" are widely recognized as the most popular, contributing to the widespread popularity of Santa's reindeer.