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)
Gino Corrado
Brush and Easel Waiter (uncredited)
Pat Flaherty
Policeman #2 (uncredited)
James Griffith
Royal Roof Orchestra Leader (uncredited)
Tippi Hedren
Ice Box Petty Girl (uncredited)
Movita
Carmelita Moray (uncredited)
Ray Teal
Policeman #1 (uncredited)
Ian Wolfe
President Webb (uncredited)
Lyn Thomas
Patti McKenzie (uncredited)