Lightning is an eager young reindeer featured in the Sesame Street special, Elmo Saves Christmas. He wears a harness so that he may one day pull Santa's sleigh, a bell-laden collar and a necklace charm in the shape of a lightning bolt.
When Santa Claus is saved from being stuck in Elmo's chimney on Christmas Eve, he blames his uncalculated width on the extra bulk added to his sack by a little reindeer. Lightning had stowed away in case one of the other reindeer had become hurt on their worldly journey. Santa rewards Elmo with three wishes in exchange for his good deed, but Lightning has been scolded for not following orders.
Later, when Elmo has wished for every day to be Christmas Day, Santa returns with Lightning, expressing concern for what should come of Elmo's desires. Lightning is assigned to escort Elmo through time and space to discover the unpleasant result of what should come of a world forced to celebrate Christmas every day.