Comet is one of Santa's reindeer. He is seen in all three of the Santa Clause films, serving as Santa's personal transport to and from the North Pole whenever he isn't delivering presents in the sleigh.
In the first film, while he is shown to understand human speech, he only communicates in grunts and snorts. This changes in the second and third films, where he instead speaks in human-like gibberish that only Santa is able to understand. In both, he is voiced by Bob Bergen.