9. The Clock King
Easily one of Batman's wackier foes, a darker take on The Clock King could be the next Arkham's answer to the Mr Freeze battle from City. This clock-based enemy may not have any legitimate superpowers, but his deep understanding of time allows him to read situations and prepare perfect counters to nearly all of Batman's moves.
Fighting a foe that can predict exactly how long it'll take you to strike would make for an incredibly dynamic combat encounter, forcing the Dark Knight to strategise a new method to take down this time-centric foe.
Whether you model it after the aforementioned Mr Freeze stealth battle from City or maybe create a one-on-one encounter that sees you fake out this evil genius, there's no doubting there's some serious potential for a Clock King face off. His abilities are simply too unique to pass up, and would add some seriously subversive mechanics if he were to battle the Caped Crusader.
This next Arkham game is going to need side-bosses after all, and seeing as some of Batman's wackier foes have featured in a supporting role in other entries, it's not too farfetched to imagine this clock-obsessed psychopath could make an appearance in Arkham's fifth entry.