No, Robert Deniro was not in To Kill a Mockingbird.
The 1962 movie To Kill a Mockingbird tells the story of Atticus Finch, a lawyer in the Depression-era South, who defends a black man against an undeserved rape charge, and his children against prejudice.
The movie starred Gregory Peck, John Megna and Frank Overton. See full cast and crew at IMDb.
Robert De Niro, on the other hand, is a legendary Oscar-winning actor who starred in such films as 'Taxi Driver,' 'The Godfather: Part II,' 'Raging Bull,' 'Awakenings' and 'The Intern.'
See Robert De Niro full list of movies and tv shows in theaters, in production and upcoming films at TVGuide.com.