This is my prequels before Justice League:
_ Batman Begins (2005)
_ The Dark Knight (2008)
_ Green Lantern (2011)
_ The Dark Knight Rises (2012)
_ Man of Steel (2013)
_ Wonder Woman
_ The Flash
_ Batman vs. Superman: World’s Finest
_ Justice League
This is my suggestions for Justice League:
- Det. John Blake as Agent Phil Coulson
- Desaad as The Other
- Lex Luthor or Joker, as Loki
DIRECTOR:
Brad Bird
CREATIVE CONSULTOR:
Bruce Timm
PRODUCERS:
Christopher Nolan, Zack Snyder, Geoff Johns, David S. Goyer
SCREENPLAY:
Will Beall, David S. Goyer, Geoff Johns
THE CASTING:
Henry Cavill as Clark Kent/Superman
Christian Bale as Batman/Bruce Wayne
After the death of John Blake (Joseph Gordon-Levitt) at the hands of Darkseid, Batman tells them to their friends that there is still a chance of defeating the Parademonios like Darkseid in the same person, but that must work together by the army while trying to save time by taking a trip to Arkham Asylum
Batman Arkham Asylum comes to interrogating Bane asking him how he could do to contact the League of Shadows, because most likely you have already got a new leader after its defeat, Batman meets Bane has rightly , but that would have to make a long trip if you really planned to defeat all that army of demons and gods Intergalactic
Batman goes to the temple of the League of Shadows defeating all opponents, even a new bodyguard named Deathstroke is then entering the room of the new leader realizing that Ra's Al Ghul is still alive, Batman surprised responds to Ra's Al Ghul he should imagine that he had survived, because they never found his body inside the shattered remains of the monorail, Ra's Al Ghul responds to Batman after being defeated in Gotham his daughter Talia and his bodyguard Bane took his body badly injured until the reason for its existence, which had allowed him to live more than seven hundred years sowing justice throughout the world, the Fountain of Lazarus, that he had restored to life and the strength to continue in their plans to destroy Gotham but as he had defeated Bane was considering seriously try again, even thought his bodyguards Deathstroke could be an excellent choice to lead the League of Shadows, but like all Gothic Metropolis like Demons were being attacked by Intergalactic, did not wish to intervene in that kind of conflict until it was absolutely necessary, Batman responds to Ra's Al Ghul both the army Metropolis and Gotham were being defeated by the demons, not even your friends with super powers were sufficient to stop them, so we had come so far to ask for your help, I wanted to give him permission to lead the League of Shadows to save all Gotham and Metropolis, Ra's Al Ghul responds to Batman after his betrayal of the League of Shadows should kill him at that very moment, but as the world was asking for help, he would help, could lead the League of Shadows, only to change them back control of Gotham, Batman agrees, but warns Ra's Al Ghul barely back to poke their heads from shadows, would be responsible for defeat as well as he did the previous two times

Cobie Smulders as Diana Prince/Wonder Woman
Morena Baccarin as Diana Prince/Wonder Woman
Evangeline Lilly as Diana Prince/Wonder Woman
Leonor Varela as Diana Prince/Wonder Woman
Michelle Monaghan as Diana Prince/Wonder Woman
Eva Green as Diana Prince/Wonder Woman
Hayley Atwell as Diana Prince/Wonder Woman
Jaimie Alexander as Diana Prince/Wonder Woman
Tanit Phoenix as Diana Prince/Wonder Woman
Minka Kelly as Diana Prince/Wonder Woman
Meghan Ory as Diana Prince/Wonder Woman
Kelly Overton as Diana Prince/Wonder Woman
Bérénice Marlohe as Diana Prince/Wonder Woman
Serinda Swan as Diana Prince/Wonder Woman
Odette Yustman as Diana Prince/Wonder Woman
Ryan Reynolds as Hal Jordan/Green Lantern
Neil Patrick Harris as Barry Allen/The Flash
Tony Todd as J'onn J'onzz/Martian ManHunter
LOVE INTEREST CHARACTERS:
Amy Adams as Lois Lane
Blake Lively as Carol Ferris/Star Sapphiere
Mark Valley as Lt. Col. Steve Trevor
Josh Lucas as Lt. Col. Steve Trevor
Joel Gretsch as Lt. Col. Steve Trevor
NOTABLE CAMEOS:
Joseph Gordon Levitt as Det. John Blake = Agent Phil Coulson
Like the character of Phil Coulson in The Avengers, I think the Det. John Blake (Joseph Gordon-Levitt) can play a similar role linking all DC characters, and like the character of Phil Coulson become the reason to create the Justice League, but unlike Joss Whedon Avengers not seeking "revenge" for their fallen comrade, but "Justice" as originally born this superhero team
Michael Caine as Alfred Pennyword
Morgan Freeman as Lucius Fox
Gary Oldman as Commissioner James Gordon
Laurence Fishbourne as Perry White
Richard Schiff as Dr. Emil Hamilton
Monica Bellucci as Queen Hippolyta
Beyonce Knowles as Artemis
John Wesley Shipp as Jay Garrick/The Flash
Judi Dench as Joan Garrick
Aaron Johnson as Dick Grayson/Robin
Anne Hathaway as Selina Kyle/Catwoman
Liam Neeson as Henri Ducard/Ra's Al Ghul
Tom Hardy as Bane
MINI-CAMEOS:
Kevin McKidd as Arthur Curry/Aquaman
Matthew McConaughey as Oliver Queen/Green Arrow
Simon Baker as Oliver Queen/Green Arrow
Ali Larter as Dinah Lance/Black Canary
VILLIANS:
Kevin Grevioux as Darkseid
Julian Richings as Desaad
Billy Zane as Lex Luthor
Angela Bassett as Amanda Waller
MI IDEAL:
My ideal would have been to include the character of the Joker in this Fan Casting, but as the actor who played him (Heath Ledger) died of an accidental drug overdose in 2008 I have been unable to add another actor to take its role in a Batman movie or maybe even a sequel to the Justice League