Todd Phillips Director, Screenwriter, Producer Joaquin Phoenix Arthur Fleck Actor Lady Gaga Harley Quinn Actor Zazie Beetz Sophie Dumond Actor Brendan Gleeson Jackie Sullivan Actor Catherine Keener Maryanne Stewart Actor Steve Coogan Paddy Meyers Actor Jacob Lofland Actor Harry Lawtey Harvey Dent Actor Scott Silver Screenwriter, Executive Producer Joseph Garner Producer Emma Tillinger Koskoff Producer Mark Friedberg Executive Producer, Production Design Georgia Kacandes Executive Producer Jason Ruder Executive Producer Michael E. Uslan Executive Producer Lawrence Sher Cinematographer Jeff Groth Film Editing Hildur Guðnadóttir Original Music Erica Hohf Art Director David Meyer Art Director Karen O'Hara Set Decoration Arianne Phillips Costume Design Francine Maisler Casting