Suggestions by @richman

Batman (Bruce Wayne)

as Bill Skarsgård in What if this actor played

Lex Luthor

as Bill Skarsgård in What if this actor played

Brainiac (Vril Dox)

as Geoffrey Rush in What if this actor played

Professor Hugo Strange

as Donald Sutherland in What if this actor played

Wildcat (DC Comics)

as Glen Powell in What if this actor played

Booster Gold

as Glen Powell in What if this actor played

Han Solo

as Glen Powell in What if this actor played

Green Lantern (Hal Jordan)

as Craig Wasson in What if this actor played

Green Arrow (Oliver Queen)

as Alan Ritchson in What if this actor played

Booster Gold

as Alan Ritchson in What if this actor played

Batman

as Alan Ritchson in What if this actor played

Nick Fury (Marvel Cinematic Universe)

as Laurence Fishburne in What if this actor played

John Stewart

as Laurence Fishburne in What if this actor played

Otto Octavius

as John Malkovich in What if this actor played

Red Ghost (Marvel Cinematic Universe)

as John Malkovich in What if this actor played

Freddy Krueger

as Willem Dafoe in What if this actor played

Harvey Bullock

as Clancy Brown in What if this actor played

Commissioner James Gordon

as Clancy Brown in What if this actor played

Private Leonard "Gomer Pyle" Lawrence

as Philip Seymour Hoffman in What if this actor played

Kingpin (Wilson Fisk)

as Philip Seymour Hoffman in What if this actor played