Leonardo DiCaprio

J. Edgar Hoover

Armie Hammer

Clyde Tolson

Naomi Watts

Helen Gandy

Josh Hamilton

Robert Irwin

Geoff Pierson

Mitchell Palmer

Cheryl Lawson

Palmer's Wife

Kaitlyn Dever

Palmer's Daughter

Brady Matthews

Inspector

Gunner Wright

Dwight Eisenhower

David A. Cooper

Franklin Roosevelt

Ed Westwick

Agent Smith

Kelly Lester

Head Secretary

Jack Donner

Edgar's Father

Judi Dench

Annie Hoover

Dylan Burns

Hoover as a Child

Jordan Bridges

Labor Dept. Lawyer

Jack Axelrod

Caminetti

Jessica Hecht

Emma Goldman