Suggestions by @user_102151

Denis Villeneuve

as Director in The Batman: The Killing Joke

Michael Green

as Writer in The Batman: The Killing Joke

Michael Giacchino

as Composer in The Batman: The Killing Joke

Milana Vayntrub

as Jeannie in The Batman: The Killing Joke

Jacob Tremblay

as Dick Grayson/Robin in The Batman: The Killing Joke

Thomas Brodie-Sangster

as Jason Todd/Robin in The Batman: The Killing Joke

Nicholas Hoult

as Dick Grayson/Nightwing in The Batman: The Killing Joke

Forest Whitaker

as Lucius Fox in The Batman: The Killing Joke

Vincent D'Onofrio

as Det. Harvey Bullock in The Batman: The Killing Joke

Anthony Hopkins

as Alfred in The Batman: The Killing Joke

Karen Gillan

as Barbara Gordon in The Batman: The Killing Joke

J.K. Simmons

as Commissioner Jim Gordon in The Batman: The Killing Joke

Joaquin Phoenix

as Joker in The Batman: The Killing Joke

Ben Affleck

as Batman in The Batman: The Killing Joke