With Black Mask being conformed to be in the DCU my choice would be Ben Mendelsohn.

He would be an ideal Black Mask because he excels at playing refined yet ruthless villains.

From the calculating Orson Krennic in Rogue One to the power hungry executive in The Dark Knight Rises and the corporate tyrant in Ready Player One, he’s shown he can embody the polished businessman façade while unleashing sadistic cruelty.

At the same time, roles like Animal Kingdom prove he can go big and unhinged when needed, giving him the range to capture both Roman Sionis’ controlled mob boss persona and his explosive, theatrical brutality.