Jared Leto's Joker appearing in Zack Snyder's Justice League has reignited interest in the original plans for the DCEU, including Ben Affleck's solo Batman movie. The four-hour "Snyder cut" contains numerous introductions and teasers for now-canceled DC films. Among them was the Batman film Ben Affleck was set to star in and direct (that project eventually became the upcoming The Batman starring Robert Pattinson). Despite what the Knightmare epilogue suggests, however, there's no confirmation that Joker would have been involved.
Based on what is known about the plans for Affleck's Batman movie, the movie's main villain would have been Joe Manganiello's Deathstroke, who also appears in Zack Snyder's Justice League meeting with Lex Luthor. Affleck aimed to tell a dark, personal story that would see Deathstroke pushing Bruce Wayne to his limits and targeting those close to him. However, Affleck was forced to pull out of the film due to health reasons, with Matt Reeves stepping in as director to tell a different story. This means that there is no clear answers as to what the final film would look like or if it would have incorporated additional villains.
While Deathstroke was slated to be the central villain in Affleck's Batman, there would have been opportunities to incorporate the Joker in a cameo or supporting role. The draft story saw Batman visiting Arkham Asylum, the infamous home for Gotham City's temporarily-imprisoned villains. A trip to the Asylum would have been the perfect opportunity to revisit the Joker, along with other Batman villains from films past. If Affleck's DCEU story involved Batman wrestling with his morality and his sanity being tested, the Joker could have been a perfect counterpoint to show what Bruce Wayne feared becoming.
Jared Leto's Joker appearing in Arkham Asylum would have been in-line with the DC Universe's approach to featuring the character. Warner Brothers clearly sees the Joker as a core part of its universe, featuring the character both in central roles, as in Joker, and smaller appearances like in Suicide Squad and the Snyder Cut. Even a small Joker scene would have been a point of discussion and hype going into the release of Affleck's Batman. This still leaves open the question of whether the Joker would have been played by Jared Leto, however, or another actor.
Leto's appearance in Suicide Squad was divisive and frequently criticized, but his second turn as the Joker in the Snyder Cut may have redeemed him. The plans for the DC movies going into Justice League and Affleck's Batman saw the franchise as being a much more closely-knit and connected movie series like the Marvel Cinematic Universe, so it would have made sense to use consistent casting across the titles. Even if Zack Snyder was never directly involved with Affleck's Batman, there would have been an attempt to make the movie consistent with his vision for the DC universe, which could have involved Leto's Joker.
Ultimately, Leto was never officially attached to the project, and there's no way of knowing if he would have eventually been involved in Affleck's Batman or future DC movies. Warner Brothers may have been wary about having Leto back, given the backlash to his Suicide Squad performance, but with the release of Zack Snyder's Justice League leading to new appreciation for both Affleck and Leto's performances as the iconic characters, and Affleck set to reprise the Batman role in The Flash, the new and less continuity-heavy DC Expanded Universe seems open to actors reprising their old roles. So Leto may not have put on the clown make-up for the last time.
