He is voiced by Nathan Greno.
Biography from the official site
Dasher is one of the legendary eight reindeer who pull Santa's sleigh every Christmas Eve. Dasher is unflappable in his self-confidence, priding himself on his piloting skills and the extremely large amount of fur on his chest.
Dasher likes to butt antlers with his fellow reindeer to psyche himself up.
Dasher doesn’t care for peeled carrots. He likes them raw, thanks very much.
Dasher has a recurring case of Athlete’s Hoof, and has been taking advice from Dr. Autry, the Reindeer Trainer & Nutritionist, on how to best treat his ailment. Slightly embarrassed by his malady, Dasher became quite annoyed by Dancer when the latter accidentally mentioned it to the entire Sleigh Team during flying practice.