Leonardo DiCaprio as John Edgar Hoover

Armie Hammer as Clyde Tolson

Naomi Watts as Helen Gandy

Josh Lucas as Charles Lindbergh

Josh Hamilton as Robert Irwin

Judi Dench as Anna Marie Hoover

Geoff Pierson as Mitchell Palmer

Gunner Wright as Dwight Eisenhower

Dermot Mulroney as Colonel Schwarzkopf

Kaitlyn Dever as Palmer's Daughter

Adam Driver as Walter Lyle

Ed Westwick as Agent Smith

Jessica Hecht as Emma Goldman

Denis O'Hare as Albert Osborne

Lea Thompson as Lela Rogers

Damon Herriman as Bruno Hauptmann

Sadie Calvano as Edgar's Niece

Amanda Schull as Anita Colby

Roberta Bassin as Roosevelt's Secretary

Emily Alyn Lind as Shirley Temple

Barbara Keegan as Bombing Witness

Gerald Downey as FBI Agent

Jeffrey Donovan as Robert Kennedy

Geoff Stults as Raymond Caffrey

Thomas Langston as Young Boy

Lea Coco as Agent Sisk

Aaron Lazar as Prosecutor Wilentz

Cheryl Lawson as Palmer's Wife

Brady Matthews as Inspector

David A. Cooper as Franklin Roosevelt

Kelly Lester as Head Secretary

Jack Donner as Edgar's Father

Dylan Burns as Hoover as a Child

Jack Axelrod as Caminetti

Michael James Faradie as Bureau Agent (1919)

Josh Stamberg as Agent Stokes

Christian Clemenson as Inspector Schell

Billy Smith as Secret Service Officer

Ken Howard as Harlan Fiske Stone

Zach Grenier as John Condon

Johnny Cicco as Young Agent

Steve Monroe as Restaurant Host

Stephen Root as Arthur Koehler

Gary Werntz as Attorney General

David Clennon as Senator Friendly

Michael O'Neill as Senator McKellar

Eric Larkin as Fred Hunter

Eric Frentzel as William Mahan

Kyle Eastwood as Stork Club Band

Gregory Hoyt as Agent One

Jenny Phagan as Baker's Wife

Chris Caputo as Bronx Baker

Shannon McClain Robertson as African American Woman (as Shannon McClain)

Leslie Augustine as Lindbergh Nanny (uncredited)

Jennipher Foster as Lucille Ball (uncredited)

Belinda Gosbee as Gangster's Moll (uncredited)

Elizabeth Karr as Secretary (uncredited)

Martin Luther King Jr. as Self (archive footage) (uncredited)

Lindsay Lucas-Bartlett as Hollywood Starlet (uncredited)

Pat Nixon as Self (archive footage) (uncredited)

Richard Nixon as Self (archive footage) (uncredited)

Jamie Noel as Racetrack Gambler (uncredited)

Miles Fisher as Agent Garrison

Robert Fleet as Edgar's Mother's Doctor

Emily Banks as Radical Citizen (uncredited)

Scot Carlisle as Agent Williams

Ryan McPartlin as Lawrence Richey

Taylor Tunes as Film Premier Attendee (uncredited)