Robert Cummings

George Petty, aka Andrew 'Andy' Tapp

Joan Caulfield

Prof. Victoria Braymore

Elsa Lanchester

Dr. Crutcher

Melville Cooper

Beardsley (Petty's butler, aka Uncle Ben)

Audrey Long

Mrs. Connie Manton Dezlow

Mary Wickes

Prof. Whitman

Frank Orth

Moody (process server)

John Ridgely

Patrolman

Dorothy Abbott

December Petty Girl (uncredited)