Fredric March (Mark Twain)
Alexis Smith (Olivia Langdon)
Donald Crisp (J.B. Pond)
Alan Hale (Steve Gillis)
C. Aubrey Smith (Oxford Chancellor)
Thurston Hall (Actor/Actress)
Frank Mayo (Actor/Actress)
Harry Hilliard (John Greenleaf Whittier)
Bobby Larson (Actor/Actress)
Robert E. Homans (Actor/Actress)
Frank Reicher (Actor/Actress)
Lee Powell (Actor/Actress)
Joseph Crehan (Ulysses S. Grant)
Diana Barrymore (Actor/Actress)
Joyce Reynolds (Clara Clemens)
Whitford Kane (Joe Goodwin)
Percy Kilbride (Billings)
Nana Bryant (Mrs. Langdon)
Dick Jones (Sam Clemens at fifteen)
Kay Johnson (Jane Clemens)
Jackie Brown (Sam Clemens at twelve)
Michael Miller (Tom Sawyer)
Joseph Crehan (Promoter)
Cliff Saum (Prospector)
Harry Tyler (Assistant Editor)
Roland Drew (Editor)
Douglas Wood (William Dean Howells)
Willie Best (George)
Burr Caruth (Oliver Wendell Holmes)
Brandon Hurst (Ralph Waldo Emerson)
Davison Clark (Henry Wadsworth Longfellow)
Monte Blue (Captain)
Paul Newlan (Boss Deckhand)
Ernest Whitman (Stoker)
Emmett E. Smith (Repeater)
Pat O'Malley (Captain's Mate)
Chester Conklin (Judge)
George Lessey (Henry H. Rogers)
Dorothy Vaughan (Kate Leary)
Lynne Baggett (Susie)
Carol Coombs (Clara as a Child)
Joyce Tucker (Jean)
Paul Scardon (Rudyard Kipling)
John Carradine (Bret Harte)
William Henry (Charles Langdon)
Robert H. Barrat (Horace E. Bixby)
Walter Hampden (Jervis Langdon)