Suggestions by @dplott

Emily Browning

as Joan in CASTLE

Ray Winstone

as Kingpin (Small Cameo Only) in CASTLE

Jake Busey

as Martin Soap in CASTLE

Cillian Murphy

as Finn Cooley in CASTLE

Stephen Lang

as The Russian in CASTLE

James McAvoy

as Jigsaw in CASTLE

Karl Urban

as Bushwhacker in CASTLE

Jennifer Tilly

as Ma Gnucci (Flashback scene only) in CASTLE

Matt Bomer

as David Lieberman in CASTLE

Joe Manganiello

as Frank Castle in CASTLE

Cara Delevingne

as Harley Quinn in “The Batman” fancast

Dylan Kingwell

as Dr. Langstrom/ The Man-Bat in Batman: Knightfall

Paul Anderson

as The Penguin/Oswald Cobblepot in Batman: Knightfall

Mark Henry

as Killer Croc/Waylon Jones in Batman: Knightfall

Natalie Dormer

as Poison Ivy in Batman: Knightfall

Michael Cerveris

as Professor Pyg in Batman: Knightfall

Gerard Butler

as Death stroke/Slade Wilson in Batman: Knightfall

Cara Delevingne

as Harley Quinn in Batman: Knightfall

Jensen Ackles

as Red Hood/Jason Todd in Batman: Knightfall

Logan Lerman

as Red Robin/Tim Drake in Batman: Knightfall