Ross Bagdasarian Jr.Alvin / Simon / David Seville (voice)
Janice KarmanTheodore / Tommy's Sister (voice)
Frank WelkerSanta Claus / Doctor (voice)
Charles BerendtClyde Crashcup (voice)
R.J. WilliamsTommy Waterford (voice)
June ForayMrs. Waterford / Mrs. Claus