Leonardo DiCaprio as Howard Hughes

Cate Blanchett as Katharine Hepburn

Kate Beckinsale as Ava Gardner

John C. Reilly as Noah Dietrich

Alec Baldwin as Juan Trippe

Alan Alda as Senator Ralph Owen Brewster

Ian Holm as Professor Fitz

Danny Huston as Jack Frye

Gwen Stefani as Jean Harlow

Jude Law as Errol Flynn

Adam Scott as Johnny Meyer

Matt Ross as Glenn Odekirk

Kelli Garner as Faith Domergue

Frances Conroy as Mrs. Hepburn

Brent Spiner as Robert Gross

Stanley DeSantis as Louis B. Mayer

Edward Herrmann as Joseph Breen

Willem Dafoe as Roland Sweet

Kenneth Welsh as Dr. Hepburn

J.C. MacKenzie as Ludlow

Jacob Davich as Howard Hughes (9 yrs old)

Amy Sloan as Howard Hughes' Mother

Sam Hennings as HELL'S ANGELS Stunt Coordinator

Joe Chrest as HELL'S ANGELS Director of Photography

Rufus Wainwright as Cocoanut Grove Vocalist #1

Harry Strandjofski as Crony of Louis B. Mayer

Vince Giordano as Cocoanut Grove Band Member

Josie Maran as Cigarette Girl

Justin Shilton as HELL'S ANGELS Pilot

Arthur Holden as Radio Announcer

Raymond Ducasse as Roscoe Turner

Joseph P. Reidy as Aide to Howard

Stéphane Demers as Maitre d'

Yves Jacques as Waiter

Loudon Wainwright III as Cocoanut Grove Vocalist #2

Jason Cavalier as Cocoanut Grove Patron

Chris Ufland as Engineer

Al Dubois as Pan Am Executive #1

Alan Toy as Man on Crutches

Sebastian Tillinger as Timer

Francesca Scorsese as Little Girl

Charlotte Scott as Little Girl

James Bradford as Uncle Willy

Joe Cobden as Another Guest #1

Linda E. Smith as Another Guest #2

Alan Fawcett as Chairman MPA

Jordan St. James as Hughes' Aide at Censor Hearing

David Purdham as Emcee

Kevin O'Rourke as Spencer Tracy

Lisa Bronwyn Moore as Noah's Wife

Emma Campbell as Jack Frye's Wife, Helen

Martha Wainwright as Cocoanut Grove Vocalist #3

Vincent Laresca as Jorge

Matt Holland as Hughes' Staff Person

Dennis St John as Custodian

Keith Campbell as Marine

Al Vandecruys as Doctor

James Rae as FBI Agent

Kathleen McAuliffe as Brewster's Maid

Nellie Sciutto as Secretary

Terry Haig as Another Senator

James McNamara as James McNamara (voice)

John Koensgen as Pan Am Executive #2

Vladimir Kuznetsov Smith as Caretaker

Mark Akeson as Caretaker

Jason Pollard as Caretaker

Heather Petrone as Vivien Leigh (uncredited)

Danielle Franke as Esquire Starlet (uncredited)

Meghan Elizabeth as Starlet (uncredited)

Elizabeth DeCicco as Starlet (uncredited)

Elisa Dyann as Coat Check Girl (uncredited)

Isabelle Champeau as Editor (uncredited)

Al Coronel as Bi-Plane Mechanic (uncredited)

Gerardo Lo Dico as Military Officer (uncredited)

Anne V. Coates as Howard Hughes' Film Editor (uncredited)

Brian T. Lynch as Ground Crewman