David Ayer wanted The Joker as the main baddie in 'Suicide Squad'.

The 49-year-old filmmaker helmed the villain-centred DC Extended Universe movie which starred Will Smith as Deadshot, Margot Robbie as Harley Quinn and Jared Leto, who took on the role of Gotham City's Clown Prince of Crime.

But despite the film seeing the antiheroes going against the Enchantress (played by Cara Delevingne), Ayer wished Batman's arch nemesis was the ''main bad guy'' for the mercenary squad to battle.

He posted on Twitter: ''Believe me. I agonize over this. Yes. Joke should have been main bad guy. (sic)''

Although a sequel is in the works, Ayer stepped away from the movie to focus on 'Gotham City Sirens' but admitted he could have done things ''a little different'' to make the first film even more of a success than it was at the box office.

He continued: ''Yeah it was a big fun silly movie. It could have been a bigger success had I done it a little different. But it did great and made an impression. (sic)''

Gavin O'Connor, 53, has now stepped up to the job of helming the DCEU sequel after Jaume Collet-Serra pulled out.

Mel Gibson was previously linked with the vacant director's chair, but has quashed the speculation.

Other filmmakers in the running to helm the sequel included Jonathan Levine, Daniel Espinosa and Ruben Fleischer, who has since took over directing 'Venom' for Sony Pictures.

Joel Kinnaman admitted he ''definitely'' wants to return to the franchise as Special Forces operative Rick Flag, and confirmed work is currently underway on a script, with shooting expected to commence ''sometime'' in 2018.

Though he hasn't seen a plot for the film yet, Kinnaman, 38, knows what he'd like to see his character get up to in the sequel with the team of supervillains, which includes Harley Quinn (Robbie), Deadshot (Smith) and Captain Boomerang (Jai Courtney).