Ross Bagdasarian, Jr.

Alvin / Simon / David Seville (voice)

Janice Karman

Theodore / Tommy's Sister (voice)

Frank Welker

Santa Claus / Doctor (voice)

Charles Berendt

Clyde Crashcup (voice)

R.J. Williams

Tommy Waterford (voice)

June Foray

Mrs. Waterford / Mrs. Claus