9. He's The Titular Arkham Knight In The Upcoming Game
The Arkham Knight will be the central antagonist in the upcoming video game Batman: Arkham Knight. He has now appeared in the comic books - making his debut in February 2015 - but was conceived to be a gaming character. Little is known about the man underneath the costume, other than the fact he harbours a deep-rooted grudge against the Dark Knight and has aligned himself with another Batman villain, the Scarecrow, in order to take him down. A number of rumours about his identity have done the rounds amongst Bat-fans, with one of those rumours theorising that he could be The Joker. Aside from the grudge against Batman, the main reason behind this is The Joker's previous form for appearing in different costumes - look no further than his Red Hood guise and his usage of the Oberon Sexton identity for proof of that - but it really does seem like something of a stretch, as interesting as it would undeniably be.