Boris Karloff as Gruesome

Ralph Byrd as Dick Tracy

Anne Gwynne as Tess Trueheart

Edward Ashley as Dr. L.E. Thal

June Clayworth as Dr. I.M. "Irma" Learned

Lyle Latell as Pat Patton

Tony Barrett as Melody

Skelton Knaggs as X-Ray

James Nolan as Dan Sterne

Joseph Crehan as Chief Brandon

Milton Parsons as Dr. A. Tomic

Ernie Adams as Waiter at Hangman's Knot (uncredited)

Phil Arnold as Sneezing Bank Customer (uncredited)

Walter Bacon as Bar Patron (uncredited)

Lex Barker as City Hospital Driver (uncredited)

Eddie Borden as Bank Customer (uncredited)

Robert Bray as Sergeant (uncredited)

Robert Clarke as Fred (Police Analyst) (uncredited)

George Cooper as Stone (Bank Teller) (uncredited)

Suzi Crandall as Blonde Bank Customer (uncredited)

William Gould as Pop (uncredited)

Ben Hall as Luke (Police Stooge) (uncredited)

Harry Harvey as Humphrey (Bank Guard) (uncredited)

Tom Keene as Dr. Frankey (uncredited)

George Lloyd as Owner of the Hangman's Knot (uncredited)

Robert Malcolm as Doctor (uncredited)

Sean McClory as Officer Carney (uncredited)

Lew Meehan as Police Driver in Montage (uncredited)

Bruce Mitchell as Police Sgt. in Montage (uncredited)

Lee Phelps as Detective (uncredited)

Lorin Raker as Insolvent Borrower (uncredited)

Bert Roach as Crandall (uncredited)

Jason Robards Sr. as Bank Officer (uncredited)

Harry Strang as Tim (uncredited)

Tex Swan as Policeman (uncredited)