Will the Arkham Knight character be perhaps one of these known characters?

Joker is confirmed to be dead, so I don't think he can fit as a suspect.

If it wasn't a known character under that mask, why hide his identity? Therefore, it's a character that has appeared before instead of an original character. An original identity for an established character. That said, Hush proves me wrong, I think (I haven't read it yet, but someone may have spoiled it for me) and it could be an original character.

My wish upon a star is that the permission Rocksteady got that they were so proud of is actually permission to use another superhero from the Justice League or otherwise outside the Batman franchise; they just couldn't say that for obvious reasons.

i hope not. that was the plot of the last one

Jason Todd seems like the strongest candidate though I am hoping to see him as red hood in this game.

I think it could be Jason but then I think it would have to be somebody that appeared in one of the previous games.

When I think about the next and probably last Arkham game and its antagonist, I think of a line from a user review from the first Arkham game. I don't know who it was. It might have even been one of you. He/she was rightfully praising Arkham Asylum upon release but lamented that Rocksteady "went with the 'linebacker batman' build."

"Linebacker Batman" has stayed with me these years, and when I see pre-release images of Arkham Knight I know why. It's so I could stand here, mmmmmkay. And tell you all. In my...my best Mr. Mackey voice. That Arkham Knight...mmmkay...is probably going to be female.

Batman in the Arkham games is, in proportion to his environment, a BIG dude. Arkham Knight has a slight frame in comparison. Granted, any man in real life would be happy to have a build like the Arkham Knight...very svelte indeed. Nice pecs. Good abs. Tight buns. And a ramrod posture you could set your watch to. Quite the specimen.

But in the Arkham games, that body could very well be a woman's body under that gear. I am going with Talia Al Ghul.