Joaquin Phoenix Arthur Fleck / Joker Robert De Niro Murray Franklin Zazie Beetz Sophie Dumond Frances Conroy Penny Fleck Brett Cullen Thomas Wayne Shea Whigham Detective Burke Bill Camp Detective Garrity Glenn Fleshler Randall Leigh Gill Gary Josh Pais Hoyt Vaughn Marc Maron Gene Ufland Sondra James Dr. Sally Murphy Guyer Barry O'Donnell Douglas Hodge Alfred Pennyworth Dante Pereira-Olson Bruce Wayne Carrie Louise Putrello Martha Wayne Sharon Washington Social Worker Hannah Gross Young Penny Frank Wood Dr. Stoner Brian Tyree Henry Carl (Arkham Clerk) April Grace Arkham Psychiatrist Mick Szal Woman on Subway Carl Lundstedt Wall Street Three Michael Benz Wall Street Three Ben Warheit Wall Street Three Gary Gulman Comedian Sam Morril Open Mic Comic Chris Redd Comedy Club Emcee Mandela Bellamy Mother on Bus Demetrius Dotson II Boy on Bus Greer Barnes Haha's Clown Ray Iannicelli Haha's Clown Bryan Callen Haha's Stripper Peter Hans Benson Good Morning Host Vito Gerbino Street Kid Adam Quezada Street Kid Xavyer Ureña Street Kid Evan Rosado Street Kid Damian Emmanuel Street Kid Jeff McCarthy NCB Anchor John Cenatiempo Aftermath Police Officer James Ciccone Murray Franklin Band Justin Theroux Ethan Chase (uncredited) John Cashin Arkham Patient (uncredited) Blaise Corrigan Taxi Driver (uncredited)