Premise : Imprisoned convicts of Belle Reve penitentiary are sent as members of Task force X to the South American island of Corto Maltese to destroy Jotunheim, a Nazi-era prison and laboratory which held political prisoners and conducted experiments.

Cast :

• Margot Robbie as Dr. Harleen Quinzel/Harley Quinn : She is first depicted as Joker’s psychiatrist in prison, then later his lover and partner in crime, before going off on her own misadventures in her DCEU appearances. Her introduction sequence in Suicide Squad mentions her as an accomplice and directly responsible for the murder of Batman’s sidekick Robin.

•  Idris Elba as Robert Dubois / BloodSport : A mercenary with a technologically-advanced suit that only he can use. After shooting Superman with a Kryptonite bullet, he shortens his prison sentence by joining Task Force X, so he can reunite with his daughter Tyla. Elba was originally cast to replace Will Smith as Deadshot before his character was changed to Bloodsport to allow Smith the opportunity to return anytime as his character in future projects.

• John Cena as Christopher Smith / Peacemaker : A ruthless killer who believes in achieving peace at any cost. Cena described him as a “douchey Captain America”, while director James Gunn said the character was straight out of a 1970s television series like Wonder Woman.
• Joel Kinnamann as Rick Falg :The heroic military leader of the Suicide Squad. Kinnaman said the film was an opportunity to give the character a blank slate, and said Flag was sillier, less jaded, more naive, and funnier in the film than his portrayal in the first Suicide Squad (2016).
• Jai Courtney as George “Digger” Harkness / Captain Boomerang : : An unhinged Australian thief who wields boomerangs.
• Peter Pacaldi as Clifford DeVoe / Thinker: A highly-intelligent supervillain.
• David Dastmalchian as Abner Krill Polka-Dot : A criminal who wears a suit covered with polka dots that are actually a variety of gadgets.
• Daniela Melchior as Ratchatcher 2: A villain who controls rats including her pet rat Sebastian.
• Michael Rooker as Brian Durlin / Savant : A vigilante computer hacker. 
• Alice Braga as Sol Soria. 
• Pete Davidson as Richard Hertz / Blackguard: A mercenary who is easily manipulated into ruining his own schemes.
• Nathan Fillion as Floyd Belkin / T.D.K.
• Sean Gunn as John Monroe / Weasel: An anthropomorphic weasel.
• Flula Borg as Javelin: A former Olympic athlete who wields Javelins as weapons.
• Mayling Ng as Mongal
• Sylvester Stallone as the voice of king Shark : A man-eating shark-human hybrid.
• Viola Davis as Amanda Waller : An agent of A.R.G.U.S. who runs the Task Force X program.