People have made their fancasts and this is my take on a JL film in the Man of Steel verse and I have put the awesome Arrow TV show into canon as well.
SPOILERS FOR ARROW SEASON 2 PRESENT
Plot
Clark Kent or Superman after his encounters with Wonder Woman and Batman has now realised he is not the only other special person on Earth and he may have to team up with some of them when a great menace threatens the earth.
Returning JL Members
Henry Caville as Clark Kent/Superman: the leader of the League
Ben Affleck as Bruce Wayne/Batman: the second in command and most distrustful of this team up idea.
Gal Godot as Diana of Themyscira/Wonder Woman: the Amazon warrior princess who shares the crush on Batman that her Justice League cartoon counterpart had
Ryan Reynolds as Hal Jordan/Green Lantern: Yes I am one of the few that genuinely likes and enjoys the film and I am a supporter of putting it in the new DC movie universe. You don’t like then tough, make your own fancast!
Grant Gustin as Barry Allen/the Flash: the new supersonic hero.
Stephen Amell as Oliver Queen/the Hood/the Vigilante/Green Arrow: a young billionaire who had spent five years on an island and after he got home he became a vigilante archer to fullfill his father’s dying wish and right the wrongs of his city. He joins with his new partner and love interest the Canary.
Caity Lotz as Sara Lance/the Canary: an assassin turned vigilante who has became partners with her old flame who is now the hooded vigilante. I know it is unknown if she and Oliver will become partners but I am going to assume she will.
New arrivals to the Justice League
Laurence Fishburne as the Martian Manhunter: got this from the Blockbuster Buster’s casting couch and I agree
Chris Hemsworth as Arthur Curry/Aquaman: I think this might not be a new choice but he has already performed a similar character as Thor and I basically mostly want to see a version of this character based on the awesome dude from the Batman Brave and the Bold film
Supporting cast:
Mark Strong as Sinestro: a cameo at the end to show a possible sequel: Justice League 2: Sinestro Corps War
Amy Adams as Lois Lane: a supporting role
Blake Lively as Carol Ferris: supporting role as well
David Ramsey as John Diggle: a cameo
Emily Bett Rickards as Felicity Smoak: same as Diggle
John Wesley Shipp as Barry Allen’s dad: mainly a casting gag since he played the Flash in that awesome old TV show that did admitingly had a silly suit (I know it is the same suit from the comics but it doesn’t quite work in real life!)
Either Cynthia Addai-Robinson or Angela Bassett as Amanda Waller: either the one from Arrow or the one from the Green Lantern film, I am not too picky
Villains
Joaquin Phoenix as Lex Luthor: the crew for Man of Steel 2 want him to play Lex so I think sure
Guy Pierce as Vandal Savage: Okay I know I will get hatemail for this, especially with the haters of the Mandarin twist in Iron Man 3 but I liked Pierce as Killian in Iron Man 3 and I want him to play the immortal manipulator similar to how he played Killian, minus the revenge scheme
No one as Starro: a voiceless computer graphic monster for the justice League to face since he was their first foe in the comics
Frank Welker as the voice of Darksied: I think the Lord of Apokolips should be played by a large man in a motion capture suit and the king of voice actors Frank Welker doing his voice, or maybe Steve Blum since he is playing him in the Justice League War film
Ray Stephenson as Solomon Grundy: truth be told I want Grundy as the villain of Man of Steel 2, hey you introduced aliens in your DC movie world Synder and Nolan so absolutely NO REASON WHY YOU CAN’T HAVE SUPES FIGHT A ZOMBIE!!!!!!!!!!!!