Grandpa is an elderly Chipmunk who appears in the Alvin and the Chipmunks Easter special The Easter Chipmunk. He lives in the same retirement village as the aunt of the easter Bunny, Mr. Hoppity. He tells the boys that he was the original "Easter Chipmunk," hinting that there could have been more after him. At first, none of the boys believe him. Simon writes it off by telling his brothers to let him believe it, because it seems to make him happy. However, over the course of the special, Alvin begins to believe him. He gets to the point where he tries to take Mr. Hoppity to court. It later becomes clear that he is in charge of delivering the Easter baskets for the whole world, while Grandpa is in charge of only four.
- It's not mentioned if Grandpa is the boys' grandfather on their mother, Vinny's side, or their birth father's, who has never been shown or mentioned at all.