Martin Scorsese Director Leonardo DiCaprio Howard Hughes Actor, Producer Cate Blanchett Katharine Hepburn Actor Kate Beckinsale Ava Gardner Actor John C. Reilly Noah Dietrich Actor Alec Baldwin Juan Trippe Actor Alan Alda Sen. Ralph Owen Brewster Actor Ian Holm Professor Fitz Actor Danny Huston Jack Frye Actor Gwen Stefani Jean Harlow Actor Jude Law Errol Flynn Actor Adam Scott Johnny Meyer Actor Matt Ross Glenn Odekirk Actor Kelli Garner Faith Domergue Actor Frances Conroy Katharine Martha Houghton Hepburn Actor Brent Spiner Robert Gross Actor Stanley DeSantis Louis B. Mayer Actor Edward Herrmann Joseph Breen Actor Willem Dafoe Tabloid editor Actor Kenneth Welsh Dr. Thomas Norval Hepburn Actor J.C. MacKenzie Ludlow Ogden Smith Actor Josie Maran Thelma Actor Vincent Laresca Jorge Actor Sam Hennings Frank Actor Chris Ufland Engineer Actor Justin Shilton Test pilot Actor Michael Mann Producer John Logan Screenwriter Chris Brigham Executive Producer, Producer Howard Shore Original Music Robert Richardson Cinematographer Thelma Schoonmaker Film Editing Ellen Lewis Casting Dante Ferretti Production Design Martin Gendron Art Director Alice Baker Set Decoration Sandy Climan Producer Charles Evans Jr. Producer Graham King Producer Francesca Lo Schiavo Set Decoration Sandy Powell Costume Design