Leonardo DiCaprio John Edgar Hoover Naomi Watts Helen Gandy Armie Hammer Clyde Tolson Josh Lucas Charles Lindbergh Josh Hamilton Robert Irwin Judi Dench Anna Marie Hoover Geoff Pierson Mitchell Palmer Gunner Wright Dwight Eisenhower Dermot Mulroney Colonel Schwarzkopf Kaitlyn Dever Palmer's Daughter Adam Driver Walter Lyle Ed Westwick Agent Smith Jessica Hecht Emma Goldman Denis O'Hare Albert Osborne Lea Thompson Lela Rogers Damon Herriman Bruno Hauptmann Sadie Calvano Edgar's Niece Amanda Schull Anita Colby Roberta Bassin Roosevelt's Secretary Emily Alyn Lind Shirley Temple Barbara Keegan Bombing Witness Gerald Downey FBI Agent Jeffrey Donovan Robert Kennedy Geoff Stults Raymond Caffrey Lea Coco Agent Sisk Aaron Lazar Prosecutor Wilentz David A. Cooper Franklin Roosevelt Kelly Lester Head Secretary Jack Donner Edgar's Father Jack Axelrod Caminetti Billy Smith Secret Service Officer Stephen Root Arthur Koehler Michael O'Neill Senator McKellar Gregory Hoyt Agent One Fileena Bahris Starlet (uncredited) Richard Nixon Self (archive footage) (uncredited)