5) The Joker
Justice League is the culmination of the growth that the DCEU has undergone over Man of Steel and BvS. However, there’s another DCEU movie rolling around as well: namely, Suicide Squad, starring Amanda Waller’s team of supervillains. It would make a lot of sense, then, if that movie’s cast could be included in some way here. And the one we want to see most in Justice League has to be the Joker.
An appearance by the Clown Prince of Crime in the movie would be an easy fit if the flashback to Todd’s death is included, as we were just saying. On the other hand, we have a feeling that there might be a trip to Arkham Asylum on the cards in the movie – seeing as Lex Luthor was moved there at the end of BvS – so it’s possible that Joker will appear in that sequence. Simply have Batman encounter Mr. J in his cell on the way to meet Luthor (presumably to discuss what he knows about Steppenwolf). It would be a great little scene that would give us the first on-screen meeting of Ben Affleck’s Batman and Jared Leto’s Clown Prince of Crime.
Previously, rumours about a Joker Justice League cameo have been strongly denied by inside sources, but we can’t help but to think that it’s still a possibility.