Suggestions by @ringothedrummer

Joel Kinnaman

as Clint the Hellrider in The Fourth Wall: The Second Chapter

Graham McTavish

as Brainiac in Ultimate Justice League

Carl Lumbly

as Ma'alefa'ak in Ultimate Justice League

Ike Amadi

as Black Manta in Ultimate Justice League

Peter Capaldi

as Thaal Sinestro in Ultimate Justice League

Jim Cummings

as The Thinker in Ultimate Justice League

Nika Futterman

as Doctor Poison in Ultimate Justice League

Alfred Molina

as Lex Luthor in Ultimate Justice League

Keith David

as The Joker in Ultimate Justice League

Grey DeLisle

as Mera in Ultimate Justice League

Mark Hamill

as Nuidis Vulko in Ultimate Justice League

Tom Scharpling

as Barry Allen in Ultimate Justice League

Susan Egan

as Lois Lane in Ultimate Justice League

Timothy Dalton

as Alfred Pennyworth in Ultimate Justice League

Phil LaMarr

as The Martian Manhunter in Ultimate Justice League

James Arnold Taylor

as Aquaman in Ultimate Justice League

Estelle

as Green Lantern in Ultimate Justice League

SungWon Cho

as The Flash in Ultimate Justice League

Sarah Michelle Gellar

as Wonder Woman in Ultimate Justice League

Troy Baker

as Batman in Ultimate Justice League