Humphrey (voice)

Wallace Shawn (voice)

Frank Hopper

Charles Haste

Rex (voice) (uncredited)

Rex (voice)

Barry (voice) / Morris Mole (voice) / Pete (voice)

Rex (voice)

Bertram (voice)

Howard Stiles

Rex (voice)

Jeffrey Engels

Rex (voice)

Mr. Mustela (voice)

Rex (voice)

Waiter

Simon Carr

Rex (voice)

Father Abruzzi

Translator

Herman

Labrador MC (voice)

Principal Fetchit (voice)

Billy (voice)

Ezra

Freud

Dr. Elliot Fibel

Vic Finley

Calico (voice)