Fan CastingReturn of the Batman

Description of The Man with the Glasgow Grin (Mid-credits scene):

In a dingy back-alley somewhere in Gotham, a man suddenly falls back against one of the walls, laughing maniacally. He then slumps onto the ground, dead, with his mouth stretched into a wide rictus. Standing above him is another man, who proclaims that Gotham is about to get "the biggest laugh of its life!" The killer then steps out of the shadows, revealing a pale white face, green hair, and red lips with scars on each side.