10. The Joker
Sure to be one of the most divisive aspects of The Batman is the last-minute inclusion of a character credited as "Unseen Arkham Inmate" but very clearly implied to be the Joker, as played by the talented Barry Keoghan.
This younger, proto version of the Clown Prince of Crime appears for an extremely brief, single-scene cameo at the very end of the film, situated in the cell next to the Riddler at Arkham State Hospital.
Though the movie doesn't outright announce him as the Joker, all the hallmarks are there: namely the fleeting glimpse of his grotesquely scarred face, and a maniacal, high-pitched cackle that's unmistakably reminiscent of Cesar Romero's 1960s Joker.
Evidently this scene teases the Joker teaming up with the Riddler and possibly other villains in the sequel. Keoghan certainly does a good job in the scene, though did the Joker really need to appear in the film at all?
It felt like studio-mandated sequel-baiting to solidify hype for the next movie, yet many would love to see the character put on ice for a while, considering how many other compelling Batman villains have never had the blockbuster treatment.