<P> When Sheriff Tate asks Scout what happened, she sees a man standing quietly in the corner behind the door of Jem's room . Atticus formally introduces Scout to Arthur Radley, whom she has known as Boo, the man who came to the aid of Jem and Scout in the woods . It is revealed that Boo had overpowered Bob Ewell before carrying Jem home . The sheriff reports that Ewell was discovered dead at the scene of the attack with a knife in his ribs . Atticus assumes that Jem killed Ewell in self - defense . Sheriff Tate, however, believes that Boo killed Ewell in defense of the children, and he tells Atticus that to drag the shy and reserved Boo into the spotlight for his heroism would be "a sin". To protect Boo, Sheriff Tate suggests that Ewell "fell on his knife". Scout draws a startlingly precocious analogy, likening unwelcome public attention to Boo to the killing of a mockingbird . </P> <P> In the order of the film's opening credits: </P> <Ul> <Li> Gregory Peck as Atticus Finch </Li> <Li> John Megna as Charles Baker "Dill" Harris </Li> <Li> Frank Overton as Sheriff Heck Tate </Li> <Li> Rosemary Murphy as Miss Maudie Atkinson </Li> <Li> Ruth White as Mrs Dubose </Li> <Li> Brock Peters as Tom Robinson </Li> <Li> Estelle Evans as Calpurnia </Li> <Li> Paul Fix as Judge John Taylor </Li> <Li> Collin Wilcox as Mayella Violet Ewell </Li> <Li> James Anderson as Robert E. Lee "Bob" Ewell </Li> <Li> Alice Ghostley as Miss Stephanie Crawford </Li> <Li> Robert Duvall as Arthur "Boo" Radley </Li> <Li> William Windom as Horace Gilmer, District Attorney </Li> <Li> Crahan Denton as Walter Cunningham </Li> <Li> Richard Hale as Nathan Radley </Li> <Li> Mary Badham as Scout </Li> <Li> Phillip Alford as Jem </Li> </Ul> <Li> Gregory Peck as Atticus Finch </Li>

Who played the lead role in to kill a mockingbird