Dora and Boots with Santa Claus.
Santa Claus is the Christmas character who appears on Christmas themed episodes.
Looks
He wears a red hat, red jacket, black boots with white fur on the edges.
Appearances
Santa Claus first appeared on "A Present For Santa" and so far his last appearance was "Dora's Christmas Carol Adventure".
Trivia
Santa Claus was voiced by Howie Dorough from "A Present For Santa".