12 Villains Who Must Appear In Affleck's Batman Movie
8. Deadshot
Despite the appeal of the idea that Deadshot will lay down his life heroically at the end of Suicide Squad, for the supervillain to suddenly turn into a good guy would be a disservice to the character. (Plus, they're not going to kill Will Smith. He's Will Smith.) He might not have the same sort of malignance that courses through the Joker's veins, but he's a killer by choice and he definitely shouldn't emerge from Suicide Squad as an entirely redeemed figure.
Bringing him back behind bars for Arkham Asylum would be an easy solution, but equally having him at large and playing a secondary villain in an Under The Red Hood adaptation would also work.
There's obviously some concern in casting Smith as a more typical villain than anti-hero as he appears to be in Suicide Squad (especially if Warner Bros are seeking to trade on his star status), but Smith could do with a role that makes him even more interesting.
It's still unlikely Smith would go that dark, so perhaps having him actually help Batman find out who Red Hood is (perhaps because his hard-line methods are making Deadshot's life difficult) would be the best approach.